What is wrong with the toilet?
I'm not a plumber; but, have a lot of life experiences. 1st - the "Dad" issue. We mean well; but, sometimes stuff just happens, If the toilet wasn't blocked before you think your dad broke the wax ring, there's a good chance it fell into the sewer line and that's your problem. If it was blocked before that then there's a good chance the sewer line collapsed under the concrete. My brother who lives in Florida has a home on a slab and had an identical problem. Unfortunately, it was an expensive fix. 
Either way, your first step would be to remove the toilet and check the wax issue. It's an easy job - shut off main water supply (either in the garage or possibly against an outside wall), drain supply line (possibly at water heater), disconnect supply to toilet, remove 2 bolts securing toilet to floor, and lift toilet up and out of the way. 
At this point you can check to see if wax ring is blocking drain, if not and you have necessary skills, rent a drain auger and attempt to clear drain, if not, call a professional plumber to assess problem and suggest remedies.
Good luck and stay safe.