|Try plugging it into a different USB port, if you have one, and then into a different computer. If still no joy then I'm afraid it has failed. I use flash drives on a daily basis, as part of my job, and one fails at least every 6 months - they are not the best way of keeping backups.|
If you need the data from it then data recovery companies can do the job, but expect to pay a fair bit for them to do it.
"I've always been mad, I know I've been mad, like the most of us..." Pink Floyd