microSD card not detected in 3ds nor windows, probably a corruption? where to go from here?

Hi,

I was just using my microSD card in my computer. I ejected it and put it in my 3ds, powered on my 3ds and received this message:
"Cannot display the software on the microSD card. The microSD card could not be accessed".
My theme had disappeared from the home menu.
All my home menu games have also disappeared.
The only icons showing up is Twilightmenu and the other regular icons such as music, download play, settings, eshop etc.
None of the CFW icons such as FBI or Luma3dsupdater are showing up on the home menu, they've disappeared.

I can't plug in my microSD into my computer as Windows says I must format it to use it.
I say no as I don't want to wipe all my 3ds data and therefore I can't access the files.
I attached photos with the Windows errors.

I made a backup of all the files on the microSD exactly 2 months ago, so should I format the SD card (in order to access it) and copy and paste the backed up files from my PC?

The worries I have with this are that I have put new files and started putting themes on the 3ds since that backup, so will anything happen with the 3ds if I restore an old backup?
I've also just been generally playing games.
Could my console be facing a brick if I do this, if so what should I do?
Any other advice on what I should do, I'm very concerned right now?

Thanks in advance.

Edit:

Its a new 3ds xl just to clarify

 

Thanks for confirming.

I formatted the SD, ran h2testw without any errors, and I copied the backup over to the SD.

Everything works just fine now, so thanks again!