How to format protected SD Cards?

My SD Card for my Nikon D5100 got corrupted so I can't see the photos when you browse it but you can still see that the card is still half full. I tried to format it but this message: "The Disk is Write Protected" keeps appearing, I already switched it to "unlock" (the switch on the left side of the card) but it's no use. What should do? Please give me all the steps to format this card.

It's pretty obvious the circuit through which the camera reads the card is bad. Have you tried uploading with a card reader or perhaps your computer has a card reader. If it does try uploading.
If that doesn't work the card is bad - your photos are history. Trash and replace.

Don't format it. If the computer can see it as half full, the SD is working properly. The folders where the files are located may be hidden. Unhide it.

Added:
To do it depends on what computer or O/S are you using. If you are using Windows 7. Try this,
Click the SD card location then click "Organize" dropdown arrow then click "Folder and search options". Check "Show all folders". Click "View". Check "Show hidden files, folders, and drives".

You didn't format the card before using
buy a new card and format it

go to google
type photo rescue