My Verbatim 350 GB external hard drive isn\'t recognized anymore.
The usual approaches to such a problem are
1) Fall back on your backups, if you have them. If you don't, learn from this and do them in the future.
2) Remove the drive from the case and attach it directly to a system's motherboard, to rule out a problem in the USB cable or enclosure
3) Download and run a recovery tool like EASEUS Partition Recovery, Recuva, or any of a dozen than get mentioned on this forum frequently. If it recovers the data, immediately copy it to another disk in case this disk is failing.
4) download and run the diagnostics from Western Digital. If the drive fails, chuck it. If it passes, it's up to you whether to trust it or not.
Good luck, and let us know how it goes.
Unasked-for advice: Do not post real contact information.