How to remove write protection in san disk pendrive

sri.student (student) (144 Points)

08 May 2012  
recently I have purchased san disk 8 GB pen drive and I started copying data to it, after copying some data, there was a message that the disk is write-protected. I have tried to remove the write protection by using regedit in the run command and making the value as 0. but the method has not solved my issue. I have done thorough virus scan check by updating the old virus scan software but to no avail! .

Can anybody suggest how to remove write protection of san disk pen drive?