Bespectacled singer/songwriter Randy Vanwarmer became one of the unlikeliest radio heroes of the late 1970s when his gentle ballad “Just When I Needed You Most” began its ascent up the Billboard chart amidst an onslaught of disco (“I Will Survive,” “Hot Stuff”) and New Wave (“Heart of Glass”).  Vanwarmer’s bittersweet memory of a long-gone lover hit a nerve with listeners looking for an escape from the dance floor.  Although the song would qualify him as a one-hit wonder, Vanwarmer continued to record and write songs for other artists until his death from…