I wanted to know a question about formatting in general. I never format a removable storage device. So my question is:

Would it help if I formatted all my usb sticks? And how would it help?

I'm asking this because I lent my brother a usb stick a few days ago. After he plugged it into his computer, it asked if he wanted to format it. He told me about it and then the usb stick is suddenly unable to work when I plugged it in my computer.

Formating a storage medum only means that you cleanout everything tat is on it and make it free again. To format simply plug the device in and go to my comupter right click on the device and click format then select the format the defalt is fat and then select quick format so that you don't have to wait so long.
Good luck