How to reset save data?

How to reset save data?

Basically, I got Omega Ruby the day before it came out because I pre-ordered it, when my dog destroyed the game cartridge 3 months later, I decided to revisit my old Pokemon games, I never managed to complete the pokedex and get the shiny Pokemon (can't remember what Pokemon it is). But when I started up the game, it skipped the little intro and the title screen, it went to a light blue screen with a white text box, inside the text box it said "The save data could not be accessed. Please turn the power off and reinsert the Game Card." This is strange because I kept the game in a little cartridge box made specifically for DS games and I've never dropped it in water or left if in dusty places. Without the title screen, I can't reset the save data, help!