IT IS every parent's nightmare - the fear of turning round in a shopping centre to find one's child has disappeared. Or that he or she has left the house on the pretext of an errand, never to return. Fung Tsui-fung's parents are the lucky ones. She at least has phoned home twice since walking out of the house on November 8 last year. But knowing their 16-year-old daughter is alive only goes some way to easing the heartache. This is a classic case of the disillusioned teenager - the kind that used to be called a ''runaway'', but who veteran social worker Mr Lau Wing says are now being referred to as the ''stayaways''. As discontent grows among Hongkong's teenagers, leading to a dramatic increase in suicide, so there is a parallel rise in the number who show their unhappiness by leaving home. A large proportion of the 4,189 people police classified as missing last yearwere teenagers. By the beginning of this year, 60 of the juveniles were still missing. Brought up by her father after her mother died 10 years ago, Tsui-fung's previous efforts to run away had landed her in a children's home. It was on a weekend visit to her Shek Kip Mei home five months ago that she walked out with only the clothes on herback. ''How I wish she would tell us where she is now. What can we do except worry?'' her heart-broken grandmother, Ms Choi Bik-kuen, said. ''We know she has a boyfriend, but we've never seen him.'' Mr Fung Bing-kwong is wracked with guilt, wondering whether he has spent enough time with his daughter. ''Maybe she wasn't given enough care in this single-parent family. ''I spent the whole day working, and when I came home I was often too tired to speak to her. It's not easy for a father with little schooling to talk to a daughter. ''I want my lost child to return. But even if I'm able to find her, I'm so afraid I would not be able to convince her to come home. ''I'm a democratic and open-minded father. No matter how naughty she was, I never smacked her or gave up on her. I always gave her a second chance and tried to explain what she'd done wrong.'' He said Tsui-fung had left school, working as a waitress in a karaoke bar in the evening. ''We all argued with her about the karaoke job. I told her time and again that she ought to lead a straight life and study more if she wanted a good future. But she never listened,'' Mr Fung said. ''The problems facing teenagers are serious, far beyond your imagination. Bad influence and temptation is everywhere.'' Mr Fung remarried last year, and Tsui-fung's stepmother said: ''In the first call home early this year she asked whether her father had made a report to the police and asked why he did it. She obviously felt unhappy. ''Tsui-fung phoned her grandmother again last month telling her to urge her father to cancel the case with the police. Her father's reply was 'how can I do that when you're not home?'. ''She does not know how much we care for her,'' Mrs Fung said. ''When she was in a girls' home we often visited her and bought her a birthday cake, although she always looked indifferent and wanted to leave the place. ''In previous cases she just left by saying she was going out. That's it. She didn't carry any luggage when she left the last time. I think she needs both a social worker and a psychiatrist; she never seems to be able to understand what we've told her.'' Mr Lau, of the Breakthrough Counselling Centre, said the problem was becoming as serious as student suicide. ''In the past, children ran away because their parents beat them and abused them,'' he said. ''The growing number of student suicides has prompted parents to stop pressurising their children. And a new sub-culture has formed in which teenagers tend to stay out just for fun with their peers.'' One grazing ground for disaffected teenagers is the Tsim Sha Tsui waterfront area. At night, police and Outreach social workers go there, looking for those known to be missing, searching them out from among the crowds of faceless youths. Four teenagers interviewed by the Sunday Morning Post at the waterfront on Friday night said they were fed up with their ''boring'' studies and work. ''If we had more money, we would go shopping, watch movies, read comics and go to discos or karaoke lounges,'' said Dennis, a Form Four student. His friend Albert butted in: ''We can have lots of fun chatting and drinking beer like this if we haven't got much money to spend. We chat about girls and things until daybreak.'' Clad in denim jacket and loose-fitting jeans, Anthony wore a cap on his head and played with the skateboard under his feet. ''How do I look?'' he asked. He had been skateboarding in Tsim Sha Tsui East since 3 pm that day, he said. Dennis and Albert said they were comics addicts, and usually read about 10 copies a week. They considered themselves adults and could not understand why their parents treated them like children by putting restrictions on them. Albert said he won $3,000 from betting on the horses a few months ago, and treated his friend to an expensive dinner. They then spent the night in a karaoke lounge, only leaving at 3 or 4 am. They said their parents would always wait for them to call home, and never reported them as missing to the police to avoid trouble. Such teenagers are easy prey for roaming gangs, who offer them cannabis and cough-syrup, or bully them into fights. Another hazard were the police, they said, who were always questioning them. Mr Lau said the rate of missing teenagers was seasonal, and he expected a huge number to go missing during the Easter holidays. ''Many parents phone us, seeking advice on how to handle their habitually missing children. ''We tell them to discuss the problem openly and calmly with their children, and try to set some guidelines for both to follow. For example, they can reach an agreement with children requiring them to tell them where they are going, for how long and withwhom before giving them the go-ahead. ''But parents' fears are justified, as it is not uncommon for teenagers to pick up soft drugs, to smoke, and engage in sex.'' Mr Lau said the lure of 24-hour shops, shopping malls, and holiday resorts as well as teenagers' rising affluence (many work part-time) accounted for the ''stayaway'' craze. He added that teenagers who habitually disappeared for fun at weekends or holidays amounted to about five per cent of those he dealt with, while those who left home occasionally constituted about 10 per cent. ''There is a trend that those who disappear occasionally will become habitual runaways eventually. Teenagers tend to stay outside one or two days at first, and then longer if parents become hostile about it. ''If they have already planned to stay outside, they usually save up money to do it. I think those who leave because of a quarrel with their parents won't stay away from home too long, because it's spontaneous and they haven't prepared enough.'' Ms Tracey Lee, of the Regional Missing Persons Unit, New Territories North region, said: ''When a youngster is reported as missing, we speak to friends, relatives . . . anyone close. We check the school, speak to teachers, see who the person is closest to. ''We go to the places they like to go to, like amusement centres, skating rinks, parks, and bowling alleys. They are rarely hard to find. Juveniles often don't go very far. I would say the hardest people to find are adults, because they can do and go where they want. By law, you cannot make someone over the age of 21 go home,'' she said. The names of missing people are entered into a central computer to make it easier for officers on the beat to identify them. ''After 28 days, if a person is still missing, I'll send my boss a memo and we have to consider a different plan of action,'' Ms Lee said. ''After the youngster has been found, we will get the parents into our office and try to find out exactly what the problem is. ''We try to calm things down so that everyone goes home happy.''