Sounds to me like the solenoid on the starter not kicking the starter in or the battery terminals are corroded. If you check the battery with a Load tester and the reading is below, 9.6 the battery is probably bad. Make sure your Alternator belt is tight, as well as making sure the cable connections are very clean, if the cable connections are not clean, the car might start, but it won't recharge correctly. Usually but not always, a starter will give you a few little warning signs that something is wrong, maybe slow turning or a Click then it will work, although it is possible they will just not work suddenly. Also, is the Starter the original one from when the car was new? or has it been replaced before? If it has been replaced before, you might have a Warranty on it, depending how old it is. If you have access to the starter, you can also tap it with a hammer while someone turns the key, Be very careful only hit the Large part of the starter housing, not the small part, and be careful about moving objects under the hood, "Fans,belts, pulleys"
I would also recommend checking your main fuse. I am pretty certain the horn is not on this fuse but everything else is. It should be a large fuse in the engine area fuse box located near the back of the engine at the base of the windshield. It should be about an 80 amp fuse (different looking than the others). Okay the most common issue is missing fuel when this happens it is the main relay is bad located under the drivers dash it controls the fuel pump.The other common issue is the ignition control module in the distributor or the coil are failing .These need to be checked next.
Good luck, Be safe.