if you're using windows 7
Open a command prompt window (start –> run –> type in the run window cmd
In the command prompt type "diskpart" Type "list volume" this will list all the drives on your computer and give them all volume numbers.
Next you want diskpart to set focus on the write protected drive "select volume #" which ever volume is the disk in question.
Now enter "attributes disk clear readonly" and then type "attributes volume clear readonly"
Check the drive in question, you should now be able to access the disk with full permissions.
if in XP open registry (regedit.exe)
then open the root : HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Storagedevicepolices .... search for "write protected " now set the value to "0"