if you've recently updated both your emuMMC and sysMMC, you'll definitely need to update your sigpatches as well, unless you're already on the latest version right now? You can download them from
this thread. If your game has stopped working after a system update, you can check
this thread for some troubleshooting info.
I usually reinstall the game with
DBI with the latest update as well. if that doesn't fix it, I clear the system cache by going into maintenance mode on emuMMC. Those two steps usually work for me.