i have the same problem with that autorun.inf virus.
i followed the instructions you have given, but still, nothing happen.
i already deleted and tried formatting but that autorun keeps on coming back.
Try using this tool - Flash Drive Disinfector
Information and Download Flash_Disinfector.exe by sUBs from >here< and save it to your desktop.
[*] Double-click Flash_Disinfector.exe to run it and follow any prompts that may appear.[*] The utility may ask you to insert your flash drive and/or other removable drives including your mobile phone. Please do so and allow the utility to clean up those drives as well.[*] Wait until it has finished scanning and then exit the program.[*] Reboot your computer when done. Note: Flash_Disinfector will create a hidden folder named autorun.inf in each partition and every USB drive plugged in when you ran it. Don’t delete this folder…it will help protect your drives from future infection.
Follow David’s instructions or, let your USB drive plugged and run Autorun Eater or Flash Disinfector, allowing them to clean up all drives. They would create hidden folders named autorun.inf in each partition and every USB drive plugged in when you ran it. These folders protect your drives from future infection. After that, reboot your computer.