App crashes while loading with error in main.m

I'm trying to recover an app that I accidentally deleted and managed to do it through the organizer, however, now when I try to run it on the simulator or iphone, it crashes with an error popping up in the main.m file:

int main(int argc, char *argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}

The error occurs in the "return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));" section of the file with the SIGABRT error. I am using Xcode 4.2 with ARC on. I am testing it on ios 4.3 and ios 5.0. The app was working before and in fact, is on the app store right now. Anything would help