I'd go into Disk Management (part of Windows) and see what it says. Assuming it isn't physically broken by that defective USB port, repartitioning and reformatting it should make it usable again.
You'll lose all data on it, of course. If fact, you already lost them. With USB-keys only used for temporary storage that shouldn't be an issue.
So I was troubleshooting a broken USB port on an ACER Aspire One netbook and I was using my USB flash drive to test the port...now the drive doesn't work at all...it shows up in Windows XP SP3 as a Removable Disk and if you try to open it it says "Please Insert a Disk". It doesnt show up in Computer at all in Windows 7 Ultimate x64. I also tried opening it in Ubuntu Lucid to see if it was just a Windows problem and it shows up there as a XXXXXXXX U1169CONTROLLER USB Device. It also shows up as that in the Windows Device Manager. Google just takes me to sites that are in Russian which is no help because I do not speak Russian. I have access to Windows XP Pro SP3 and Win7 Ultimate x64 as well as Ubuntu Lucid Lynx. Any ideas would be helpful. Thanks!