I come home from work explorer was running fine, went back out and hour later to run to store vehicle is acting all sorts of crazy.

Symptoms :
Missing will barely run
White smoke
Oil at bottom of motor on driver side
OIL leaking from muffler
Motor knocking/ticking

Please help what could be wrong?

 

You might check the oil level to see if it ran out of oil in which case serious damage may have been done to the engine. With oil coming out of the exhaust system, it may be too late to save the engine.

 

It has oil in it we never run it low on oil....

 

Did you just purchase fuel on the way home?
Have seen symptoms like these when diesel fuel was put into gas engine vehicle.

 

Yes I did

 

Was the pump handle Green, which could indicate diesel fuel. If it was diesel fuel , no big deal. The fuel lines should be purged out, the tank emptied and fuel filter replaced. The spark plugs should be removed and cleaned a little. You probably would only need to remove some of the plugs just so it will try to run on a couple cyls and flush the diesel fuel out. This was a common problem with large trucks that had gas engines and people assumed they were diesels and pumped diesel fuel into the tank.
Lets hope that's all that happened here.