Remove Write Protection

Two ways available:

Either make a registry key edit ( http://answers.microsoft.com/en-us/windows/forum/windows_vista-performance/external-hard-drive-remove-write-protection/6320592e-3986-4e9a-9df2-ab0d1e8e85cc ) or use diskpart:

Open the command prompt box with right click and run as administrator

Type each of these commands one at a time in this order:
diskpart
list volume
select volume n (where n = the problem volume)
attributes disk clear readonly
attributes volume clear readonly

After each of the last two you should get a response that it was successful.

Your drive should now be both read and write capable.