Trouble after replacing valve cover gasket

"The head gasket is what ensures that no oil or coolant gets into the cylinders.

Valve cover gaskets ensures no oil leaks out of the valve train.

Engine turns over but no fire? Or does not turn over at all?

Check oil dip stick for a foamy build up, this will indicate water is in the crank case and indicate that there is an issue the head, it could be warped or cracked or the head gasket is blown and oil and coolant is getting in and fouling your spark plugs."