This is a long shot, but since there are no other solutions posted I thought I would suggest it.
Plug your flash drive into a USB port. Go to Start>Run>diskmgmt.msc>Enter. This will bring up the disk mgmt console. See if your flash drive is displayed there. If it is, it may just need formatting or assigning a drive letter to it. To do both, right click on the flash drive and select "New Simple Volume". This is pretty self explanatory. For file system, select "Fat 32". For Cluster Size select "Default". Pick an appropriate drive letter when prompted. Finish the wizard and then go into Computer and see if your drive is now visible?
Another option is to just assign a drive letter, as flash drives are usually formatted already when you get a new one, but not "ALWAYS" which is why I posted the above recommendation first.
Anyway, go to disk mgmt, as above and right click on your flash drive. Look for "Change Drive Letters and Path" and select this. You will see a new simple wizard to choose a drive letter and assign it to your flash drive. Finish the wizard, go to Computer and see if your flash drive is displayed?
On the other hand, you may have a defective flash drive and none of this works.
Yogi