|"I downloaded all my pictures on it a few months ago from a different computer. I cannot get the flash drive to work on that computer, either."|
"... I cannot get the flash drive to work on that computer, either."
You may have damaged the data on the flash drive. Usually the data can be recovered.
Troubleshooting USB device problems including for flash drives, external drives, memory cards.
See Response 1:
Check that out first, especially the info at the last link in that. .
Rarely, not all the ports on the back of a desktop case may be able to supply 500ma each.
If you have a desktop computer, Note that I answered a Topic on this site recently where a guy had an external drive, which does require the full 500ma, connected to a port on the back of a desktop case - it would not work properly when a webcam was in the port next to it, but it worked fine when the webcam was unplugged. Ports on the back of a desktop case often have two ports connected to the same USB controller module that are ports one above the other - you could try connecting the cable to one of those and leaving the other un-used.
In your case, if the flash drive is plugged into a USB port that is next to and above or below one an external hard drive is plugged into, the flash drive or the external drive or both may not be recognized properly.