How to repair an MP3 when it is damaged or corrupted on PC?

Before trying to repair the MP3s, make a copy of the entire folder and work only on the copies. If the files were restored after a crash, the damage may have happened at the disk or file-system level, so first check whether you have OneDrive version history, File History, another backup, or the original recording device. A clean earlier copy is better than a repaired file. On Windows, also run a disk check after your files are backed up, because continuing to use an unhealthy drive can corrupt more data. For each MP3, test whether Windows Media Player can play any part of it and note whether the failure is at the start, middle, or end. If only part of the audio plays, save what you can from the playable source and keep the damaged original untouched for later recovery attempts.