Sims 4 limited edition game no longer showing up as installed

[amyyjean]

For some reason I cannot play my game. I had installed it a month ago and was running fine, but I just tried to bring it up and it is asking for my activation code. I type it in and it keeps saying the code has been used. It seems to be installed on my computer still, as I still have all my folders like the Mods and Tray. How can I get my game to run? Do I really need to reinstall it all and lose everything I've done?