well, you already know Feurio, which I guess is the program that warns you about the problems.
Those problems are corrupted frames in MP3. Some of them are audible, others not.
Remember the position of the errors and zoom the zone on the Track Editor to “visualize” the problem.
Another program that checks the errors is EncSpot.
There is no program that can recover the original data.
Maybe there are programs that can “guess” what is the lacking data, but probably doesn’t sound as it should.
You can try wave editors like Sound Forge, CoolEdit, Goldwave, and use a tool like “deglitch” to improve the sound.
Check this thread to begin:
You’d better get the original file.