Who has the answers to the problems of adolescence? To religious skepticism. Sexual promiscuity. Drinking. Venereal disease. Conformism. The Absence of adult values. Etc. Etc. Dorothy Gordon tries and it's inevitable that she should. She has moderated NBC's well-intentioned Youth Forum for twenty years. And she's heard thousands of ""young people,"" hundreds of experts, and Fannie Hurst speak on these very same questions week, after week, after week. She draws from all of them and sums up tidily at the end of each chapter. One of her early conclusions -- ""Where young people find a lack of interest and understanding in the home, they may seek it elsewhere without finding satisfaction""-- is fairly indicative of the general tenor of the book. It's moderate, intelligent, well-balanced, and fraught with the kind of homiletic good-will that gets to the heart of everything and to the guts of nothing at all. Perhaps the problem is Miss Gordon's assumption that she has worked with a cross-section of American youth. As she says, ""We have had young people representing all economic and social groups, from the son of a poor laborer to the daughter of an upper-income suburban family."" But where are the activists from Berkeley? Where are the lovely, loving pacificts? Where are the nihilists who have found the only workable solution to their problems in pot and mescalin and other chemotherapeutic escape? And where are the ""sons of poor laborers"" who don't know Youth Forum, or Dorothy Gordon because neither it nor she has any relevance what-soever to their lives past, present, or futureless? These are the ""young people"" who need answers and Dorothy Gordon supplies none of them. Edgar Z. Friedenberg in his recently published Coming of Age in America (Random House) does.