2DS Thinks The SD Card is Write Protected

When I first found the SD card in my 2DS, I took It out to try to figure out what it was (That was a very long time ago, I know what it is now). I took a look at it and then tried to put it back in, but I put it in wrong and it got stuck. I only just managed to get it out last year and put it back in the right way, but ever since then the 2DS has thought it was write protected. I now have a whole bunch of stuff that I want to play on it but I can only play stuff I have played before. Does anyone have the answer to this?