iTunes lost location for all my music

I opened iTunes today and all my music has an exclamation mark in front of it. I think no problem I'll locate one and then let iTunes find the rest. Except after locating a song iTunes doesn't ask if I want it to try to locate the rest. Is there a way to force it to do this?

More information. I look at the song info and the location iTunes is looking is correct but it has appended file:// to the beginning of the file location for every song. I've tried editing the xml file and correcting that but iTunes apparently just uses the itl file and changes the xml file back. I've tried forcing iTunes to create a new itl file by corrupting the old one but it never uses the xml file to correct it it just creates a new database from scratch with none of my files. I can use an old itl file but I'll have to re-add and modify everything that's changed since that old file was created.