can you tell me how your flash drive appear in your screen? does it appear as a drive but you can access it? does it appear as a folder or don't appear at all? when you click does it show a message no drive found?
can you check start > my computer > control panel >administrative tools> computer management > under system tool go to device manager and to right side look for human interface device left click it choose scan for hardware changes you should see a list of available usb ports choose the port your using and update driver ( if you don't know which one just update all ports.
go to disk management click it, you can see all drivers there and their status see the driver you want left click and you can see list of option you can open it or choose format to format it , if not opening it either virus infected you can scan it with antivirus to fix it then format it to get it working , if damaged you might need low-level format can be done downloading low level format utility or using drive date recovery utility should fix the problem if not heavily damaged. you can find those utilities by search in google or in software webs.