Can’t Format My Pen Drive

I HAVE 1 GB MOSERBAER PEN DRIVE. AND THERE ARE VIRUS IN IT. WHEN I SCAN THIS PEN DRIVE BY AVG 7.5,VIRUS DECETED AFTER HEALING AVG FORCED TO RESTART MY PC. AFTER RESTARTING THE PROBLEM IS SAME. VIRUS IS STILL IN IT. THE SAME CONDITION WITH SYMANTEC 10.0 ANTIVIRUS. WHEN I FORMAT IT THE MESSAGE IS DISPLAYED ” THE DISK IS WRITE PROTECT”. BUT THERE IS NO WRITE PROTECTION BUTTON ON MY PEN DRIVE. I HAD TRIED IN CMD PROMPT AS WELL AS SAFE MODE. PLEASE HELP???