I have a MacBook Pro OS X 10.10.5. At some point my Scandisk Extreme Pro 64 gb was not “read only” and I have no idea how it got this way. I feel like I have read everywhere and it seems to be a thing, but I am really not understanding how to fix it. I was able to format it (delete the photos) in my GoPro, but in my port on my computer it’s write protected. Please help so I can use the dang thing. I have only had it about a month and they ain’t cheap. Thanks in advance. 
Hello,
in that case the card seems to be defective and needs to be replaced. so i would suggest contacting sandisk for a replacement
here you can find the link for the replacment
http://kb.sandisk.com/app/rmaform/session/L3RpbWUvMTQ3NDI3NDQ5MC9zaWQvMWJGTEJfLW0%3D
