Reusing SD Card that was used for internal storage

[mdobin]

I factory reset my phone, but forgot (because I'm an *****) that I was using a 64 Gb SD card for internal storage. When the phone reset, it recognized the card and offered to format it either as internal or additional storage. I wanted to revert the card to separate use but the phone won't reformat the card. It has offered to do so, but fails while giving an error that indicates that the card is write protected.

I have found a variety of cures, including a Windows registry hack, but that doesn't seem to work.

Any suggestions. I'm feeling foolish.

Thanks.

 

[Rukbat]

Just put it into a Windows PC, right-click on the card (where it shows, along with your other drive(s), and Format. That formats it to use as external (portable) storage, which is what you want.