imovie clips missing

Hey-

I made a movie and when it was exported to make a movie it didn't give me any warnings, i burned the dvd, then when i watched it, all the video clips were missing. but i can play it back in imovie project.

on a second note, i believe all my videos were accidentally erased because i cannot find them in imovie (except the project library for the movie i made above) but my amount of free gigs has not gotten bigger so they must be somewhere on my computer.

can you tell i'm not very tech savy....

any help would be appreciated.

thanks!