When you plug in the flash drive does the light on the flash drive come on? Do you get any messages saying the drive malfunctioned or is not recognized? Is the drive seen in disk management (start -> run -> diskmgmt.msc).
Generally if the drive isn't seen on two computers (try a third one for luck) than the drive has failed.
I wrote an article describing common USB flash drive failures.
http://www.aplusperfect.com/articles/how-flash-drives-fail
If you need the data you'll need to send it into a DR shop that specializes in data recovery of flash drives. Here are some tips for locating a Data Recovery shop specializing in flash drives:
1. Make sure they recover data on the NAND or PCB level, many DR companies that "specialize" in flash drives only recover deleted files.
2. Find out how much they charge if they can't get the data, anything more than $30, look elsewhere
3. If they can't get the data contact another company, it’s very very rare when the data is unrecoverable. I get many people who took their drives to another company who either didn't know what they were doing or didn't have the proper tools to recover the data. DR of Flash drives is a relatively new field, there are many inexperienced people.
4. Find out how much they charge for NAND & PCB level recovery, to get you in the door some DR shops will quote low prices however its only for deleted files or broken usb connectors.
5. NAND & PCB level recovery starts at around $150 I've heard of companies charging $3000, generally expect to pay between $150 and $500 depending on the shop.
Here are some DR shops:
aplusperfect.com - $175 (shameless plug for my DR company)
eprovided.com - $450
ontrack - $500 - $3000
