"the System Cannot Find The File Specified Usb Format" Usb Flash Drive

I recently turned my usb into bootable usb in order to run chrome os,everything was ok untill i needed my usb to transfer some files so when i plugged it in while running windows 7 a box popped up to format it i clicked ok,then i noticed the usb from 8 giga showed up as 1 giga in my computer.I opened disk management and saw that it was cutted down in many partitions, i deleted some of them so i would expand it in one partition,at that point my trouble began,the expand option was greyed out,i tried diskpart and delete the partitions there.After that the drive lost its assign letter and showed up as one partition in disk management but in my computer it was invisible,i tried other guides that use diskpart and i download some programs to fix this with no luck.when i tried to format or assign letter from disk management i get this message "the system cannot find the file specified usb format".I tried to plug the usb in my roomates laptop with the same resaults so i dont think its my drivers or laptop problem.