vanish without (a) trace
1. To disappear without any indication to one's or something's whereabouts. Police have been searching for two weeks to find a young girl who vanished without trace from her home in Rochester. Authorities are puzzled by the navy submarine that seemingly vanished without a trace last Thursday.
2. To be forgotten about by the population as a whole, especially after being very popular. The digital pets fad took the world by storm in the late 1990s, but pretty much vanished without a trace by the end of the millennium.