Usb

There was no problem with my usb until I opened it in a friend computer.It was ok but when I tried to open in my computer it says "usb must be formatted".Now I cannot open it. Pls help.

Another usb would open showing programs like excel,words etc. I opened excel but it would not show me my files.Very strange when I saved a file, I could see all my files, I can open it but only one at a time. Everytime I had to go through the process of opening excel,save something to access my previous file. Help welcome