first - do NOT run anything on that drive - no chkdsk - nothing it may just make it more difficult to recover.
The above software is among the best; here a couple of others to try if not successfull - even free ones :
http://www.pcworld.com/downloads/collection/0,collid,1295,00.asp Free Recovery
http://www.pcinspector.de/file_recovery/UK/welcome.htm pc Inspector -free
http://www.stellarinfo.com/ Stellar
http://www.ontrack.com/ Ontrack