Anger with FFVA

I just gave my little brother permission to save in Final Fantasy 5 advance, and while I was telling him which file he could overwrite I noticed that all my other save files were gone.Just gone. I thought that was impossible! Any clue on what just happened?

Are you using an emulator or a DS (R4/M3 or the real cartridge)?

I'm using a real cartridge with a GBA

the battery that maintains the save states in RAM might be flat.