Welcome to the forums!
I am not sure just what you are asking.
Has your USB stick already failed or are you looking for advice on how to protect your data?
If you keep multiple backups of your data, you should never have to worry about loosing your data.
Myself, I keep all my data in at least three places, system hard drive, portable hard drive and in a DVDr archive.
In this way, you can ensure that no single failure will destroy your important data.
If your USB stick is not being detected, try using a different computer.
Unfortunately, USB sticks are not the most reliable place to store important data.
If another system can not detect it, there is a good chance your data is permanently lost.