Accidentally formatted SD card I used :C

[mimmsysy]

I bought this 520 in 1 cartridge (I have no idea what kind of cartridge it is) for my aunt's old nintendo 3ds that she gave me, but I accidentally formatted it and now I don't know how to bring back or download new games. I've tried doing research n stuff but I just couldn't find what I needed. I know I need to start from scratch, but I really don't mind. Please help?

Edit: Forgot to mention. I use my phone to access the SD card through my PC. Can't really afford an SD card reader right now, desperate times call for desperate measures.

 

[zxr750j]

A photo of the pcb would help, then you know might found out which card you've got and which flashcard files you need.
Downloading roms is a google problem.