Have oil in my 3rd & 4th spark plug well. engine won't start. How can I fix this

Check basics_ compression spark and fuel. Last car i saw with plug wells full of oil had a seal behind oil pump slinging the stuff like jedd clampit had just shot it.

Sounds like it is time for a serious gasket job. If you want it, it sounds like head gasket and valve gaskets are needed. Was there oil on the ground below the vechicle as well?

PUT SOME OIL RINGS ON YOUR PISTON OR BUY SOME OIL FOULERS FOR YOUR NEW PLUGS AND ALSO CHECK AND SEE IF VALVE GUIDES ARE NOT DRIED UP OR BROKEN

From the sound of it you need to get a valve cover gasket set make sure it includes the spark plug tube seals,cause thats probably where it is leaking