deleted files

I deleted some songs  on my sansa fuze  not by computer  but manually  using the fuze and now when I try to put them back on WMP says that they are still on the device and won’t sync them to  my fuze anymore  any one know how I can fix this and what  the actual problem is?

I don’t know if it will help, but sometimes the database retains information for changed or deleted files. Put the unit in MSC mode and delete MTABLE.SYS. That’s just the listing–it doesn’t affect the music. When you disconnect and it reboots,  it will make a new list of only the files still on the Fuze. 

Otherwise, it’s a WMP mystery and someone else will have to suggest something.