Formatted mp3 player

Hello,


I accidently formatted my mp3 player some time back(by accident) and lost a lot of files, however now when i try to add files i am only able to add around 400mb, however the mp3 has a capacity of 2gb. I would like to know whether or not i can get my memory back, for adding new files. i don't want the files that i lost, however the memory they used is still occupied. is there any way of freeing this space up? thank you in advance.