My MacBook Air won't recognize a flash drive.

I can see it, but it says it can't open because it can't find it. I have had more problems with Mac, and I regret buying one at this point. It's one problem after another, and this is now a new one. I can't use any of flash drives, which have important documents on them, because my lap top won't open them. It says it can't find them yet says the name of the flash drive. Any thoughts on what the problem is? I am tired of this stuff happening all the time.