need help with usb disk

hi all, i'm pretty messed up right now and need all the help i can get...my usb's been pissing me off right now!!!when i click on its properties i can see that there is still 1.30 Gb free space, i have a 16gb usb btw, but when i open the usb i can't find the specific folder (installers) which pretty much consumes the usb...all other files like documents, photos, etc..other installers which was not in the 'installers' folder can be seen. but i find it weird why is it in the properties saying i have 13+gb of used space? does my usb have a virus? please help please...thank you...

also try this in case you have hidden files on it

open any folder you want from desktop or were ever then go to

Tools
Folder Options
View select
Show hidden files and folders

delete what you want and do as SureNdrA suggested also if you want

have you installed anything from usb to your pc?
that might be the issue
if so remove any apps you install from usb off your pc then try format it

also if you have install apps from pc to you usb that run off pc do the same remove them from pc