My wife was driving our 1996 accord (2.2 l) and she heard a "snap" and the engine started making a "clanking" noise. She drove it home. My first thought was the timing belt broke, but how would the engine keep running? Also, I had the timing belt replaced last year. So after oppening the hood I found two spark plug wires off the enngine and the #4 spark plug was gone. After I pulled the #3 plug it was covered with oil. So, I know have a blown head gasket. But what else is likely? broken camshaft? Scored pistons? Also, would the engine run with a broken timing belt? Finally what would cause or where would the pressure come from to blow out the sparkplug (pressure in crankcase)? As you can tell I am not technical so any help here is greatly appreciated.

 

Definitely not the timing belt

 

Not tightening the spark plugs enough can cause them to work their way out. I would install new plugs and start it. Just loosing the plugs doesn't necessarily mean the head gasket is blown.
If the number three plug was covered in oil on the outside, you just need a new valve cover gasket set. If it was covered on the plug tip, then you have other issues.