Try varying your search criteria. For example if it's music, search just artist, or just album or just title. Likewise for video, choose a portion of the movie title or an actor or producer's name, etc. You can go to the Tools menu -> Advanced Search to get more search options.

Sometimes what I do is search a song title that I'm not after but from same album. Then if I get results, I may browse that person's files if I am able to to see if they have any more.