If you type the title in brackets into a search engine you can usually find them. For example 'Yellow Submarine'
If you just type song lyrics in it should work
The web carries a vast array of lyrics sites - often specialising in particular styles or eras. Some of the "mislheard lyrics" sites are really good fun, so if you thought Paul McCartney had one of the biggest hits ever about an Irish garage, because you thought he was singing "Mulligan's Tyres" - check out some more examples!