So I was organizing my 'originaly music' folder and when I went to add vox to a track and all of my tracks were missing their files.
Fender Telecaster w/ Dual Gibson Humbuckers
Ovation Celebrity Acoustic/Electric
Fender Frontman 212R
Old Too Young (Folk/Bluegrass/Punk)
The Orange Line (Stoner Metal/Punk/Alternative)
I think the wav files are stored separately from the actual project file in Reaper. I would recommend putting the project file back where it was and see if the files "come back."