What is causing the smoke, no acceleration, and now no start?2008 Kia Rio LX

That sounds like a blown engine.

Next time you guys have car trouble shut the thing off and have a mechanic that knows what they're doing fix it .

Definitely sounds like a blown engine. To check the oil level you pull the dipstick, wipe it off with a rag or paper towel, reinsert the dipstick, then remove the dipstick a second time. That's your oil level. Were you with your Son when this happened? If not, I'm sure there's more to this story! Fun fact, the alternator belt on this engine also drives the water pump to keep the engine cool. So, when the belt broke, for whatever reason, a red warning light came on the dash to alert your Son that the alternator had stopped working. He should have pulled over then. But he didn't, he ignored it. Since the water pump also stopped working because the belt broke a few minutes later the engine began to overheat and a second red warning light came on to alert your Son that the engine was overheating. He ignored that too and kept driving until the engine got so hot it quit! When the engine gets that hot the oil thins out to the point it's like water and does nothing to lubricate the engine. Bearings start knocking and other strange noises start sounding from under the hood before the engine actually stops! But he probably didn't hear any of that with the radio playing, very loudly no doubt! I don't think the vehicle is salvageable but it doesn't hurt to have it looked at. You can remove all the spark plugs and try to turn the engine by hand. If it won't turn, junk the vehicle, it's done. If it will turn by hand replace the starter. The excessive heat probably burned out the starter. Check for any burned or damaged wiring too. Replace the belt and find out what caused the old one to break. Unless the belt was old, like original to the vehicle, it probably didn't just break. Possibly the water pump or something seized and caused the belt to break. This would have caused a loud screeching noise which, again, your Son ignored. Hope that helps! Jim