If you used Windows system restore all of your files should still be there.
If you used the OEM (Dell,Acer,HP,etc..)recovery disk everything was wiped and gone.
You can use data recovery software to get some of the files back. BUT the more you use the computer the less chanch you have for recovery.
Professional data recovery is possible but expensive.$1200.00 up to thousands of dollars. But then again the more you use the computer the less chance of recovery.
There is some software than can recover data but once it is overwritten by new data it is all but impossible to recover. I deleted some data (did not write over it) and I used Active@Undelete but I am sure there are free programs out there.