Ok so I was just playing my game on my emulator and all of a sudden, a message pops up and says something about a mic but then the message goes away, my game restarts and i just lost about 4hours of gameplay!!!
There is nothing you can do unfortunately. No$GBA writes the save when you close the emu, not when you actually hit save, so if it crashes, it never writes the save. There is nothing you can do to get it back or stop it from happening besides restart the emu often (every hour or so). Thankfully, no$zoomer can autoload your last game making it slightly less annoying.
I have lost many hours in many games due to this issue.