Corrupt files on my external hard drive

ive got a maxtor external hard drive, never had any problems with it before but earlier today a message appeared saying that my music folder was corrupt. Didnt think much of it until i later tried to play some stuff in itunes and it said it couldnt locate any files. I looked in the folder and apparently its empty yet the space avaliable on the harddrive indicates that there are 35GB of files still there. The same thing happened to another folder on the hard drive but with no warning message. All other files on the hard drive still work and it has not undergone and damage so i dont think it is a physical fault. Can anyone tell me if it is possible to restore the missing files and how to do so?