Computer telling me I have Zero KB available on my 8 GB Fuze. How?

New problem: I cleared everything off of the player (backing it up on my computer of course) to figure this thing out. After doing this, I noticed that it now says I have only 2 GB available. It’s empty, and my 8 GB Fuze has now been turned into a 2 GB. How could this possibly happen?? Again, a hundred apologies for all the problems, but I have no clue what to do.