If the drive hardware is not being recognised, then no amount of recovery software is going to achieve anything as theres a physical fault
However if when you plug it in, the drive is recognised as a piece of drive hardware, but the system simply can't read it then you may have a chance
I have to say though that I've tried various recovery programs on flash drives in the past and never got anything off any of them. The fault always seemed to be mechanical
However if you want to try, start off with a free one called recuva
Recuva - Undelete, Unerase, File and Disk Recovery - Free Download