If you did what you state you did, you can undo it with the command DISKPART> attributes disk set readonly.
http://pario.no/2011/05/23/clear-read-only-flag-on-disk-in-windows-7-using-diskpart/ is quite clear about it.
But maybe you did something else. And maybe it's just a disk gone bad. That's a quite common happening with external disk.
Just buy another disk and get the files back from your backup. That costs $100 or so. A professional data recovery company is much more expensive. They do the work for people who forgot to backup.
I wasn't able to add or remove any of my files from my external hard drive so I attempted to fix it but only succeeded in making things worse. My computer will not even recognize it when I attach it and turn it on.
The hard drive was saying it was write protected so these are the steps I followed (I found them on another forum site) to try and fix it:
---> list volume
---> select volume #
---> attributes disk clear readonly"
I was told this would solve my issue, but it did not. Is there any way I can reverse what I've done? I have about 750G worth of my life on there and I would like to have it back.
I run Windows 7 on an HP Pavilion.