MY USB IS NOT WORKING WITH ANY PC?

I have sony 4gb usb pen drive. yesterday i have partitioned and formatted the drive. after that pen drive is not working. whenever i want to connect to a pc, it gets connected. when i want to open it it shows a message that please incert a disk into drive E. while it shows connected as Removable Disk (E) in my computer. i tried in other pc also but result is same. Please help me out.thanks in advance.