Checking the pendrive on multiple PCs was a good idea. Please check if the pendrive is recognized in Device Manager. If not, the System simply cannot get a signal that something is connected. It is highly possible that your pendrive has been damaged. If you have some important files stored on the drive, try connecting it to a Linux PC. You might get better results and the opportunity to back up some of the files. Once you do so, you may need to replace the pendrive.
Hope this helps