How do I get files from the EHD, won't allow... 1. I have a 100 GB maxtor one touch external hard

Question

1. I have a 100 GB maxtor one touch external hard drive. 2.I backed up a bunch of files and I still had over 20 GB left 3. I uncompressed it thinking that I had enough room 4. Drive can no longer be accessed because it is full. message given is :''..is not accessable the disk structure is corrupted and unreadable'' 5. is there anyway of retriving the files on here?