Small Engines (Lawn Mowers, etc.): Mower wont start, briggs and straton, spark test

Question
After mowing the yard last week, I washed down the mower with a water hose. My mower is a Murray Quantum 6.0hp. I sprayed the motor, body and underside as I have every week for as long as I have owned a mower. When I tried to start the mower today, it will not start. It has fuel and the oil level is fine. I pulled out the spark plug and cleaned it up, but it still will not fire (start). I tilted the mower onto its side when I cleaned it last week, but it has never caused a problem in the past. What do you recommend I do?
The mower is 1 or 2 years old. No prior repairs. Briggs and Straton motor.

Answer
Remove the spark plug, insert the spark plug into the wire and let the spark plug touch the engine while pulling on the rope.  You should see spark.
If you have spark, then the problem is either a bad spark plug...happens quite often, or a dirty carburetor.

Let me know about the spark test.
Eric