Cant backup computer- My Passport Ultra

ok so i first got the My Passport Ultra 2 months ago, along with my computer, macbook air. its been working fine, always backuping up and such. but today i need to do a backup since im updating to macOS sierra. i cant update becuase the last time i did (on my old mac, beta version), i lost all my things! so i need the backup! it doesnt seem register because wehn i plug it in,it says disk not availbe, even though its plugged in. i cleaned it out with a q-tip but it still doesnt work.

tl;dr: computer doesnt seem to work with the My Passport Ultra, the disk drive itslef still works.

help please! sorry if u cant understand it

Hi, are you able to see the drive in the desktop and transfer files to it?