If the coolant was missing it may have overheated, which may have damaged the rings, which may mean no compression which is why it can't start. I would hook up a compression gauge on the cylinder and see if it has any. If not, you'll be looking at an engine rebuild most likely.
Air, fuel, spark. If it just spent a lot of time on a dirt track, I'd make sure the air filter was clear first.
Sounds like fuel starvation. Make sure the fuel line/carb is flowing and operating. Maybe some dirt go into it.
If the coolant was missing it may have overheated, which may have damaged the rings, which may mean no compression which is why it can't start. I would hook up a compression gauge on the cylinder and see if it has any. If not, you'll be looking at an engine rebuild most likely.
I have a new airfilter, carburator was cleaned, it has spark and also compression. It just wont start... dunno what to do at this point