I just got the Omega Ruby game. I had played it for a few hours, then turned my 3DS off. A few days later, I picked my 3DS up to play my Omega Ruby game, but the Icon wasn't on the Home Menu. I took out the cart and put it back in, but it still didn't work. I didn't want to throw it out, because I had made some decent progress. What can I do to fix it? Most of my shiny Pokemon are on Omega Ruby!
Just try to wait a while before putting it back in and then put the game cartridge in. Wait a bit after that and don't touch the game. Turn it on and it should be there. If not, maybe you did something wrong while removing the cartridge. Was the 3DS off when you took it out? Anyway, here are a few more options-
Hope I've helped!