Small Engines (Lawn Mowers, etc.): lawnmower fails to start, internal passages, hp briggs

Question
I have a lawnmachines brand lawnmower with a 4 hp briggs&straton engine. I have only had it for two years and i just got it out of storage for the summer. I have tried repeatedly to start this thing with no luck. I have absolutly no clue about engines. Can you offer any advice?  

Answer
If you left fuel in it, you will need to clean the carb thoroughly including pushing a piece of tag wire through all of the internal passages.  You will also need to drain and clean the fuel tank.  Start with a clean system and fresh fuel.  Then you should replace the spark plug and check for spark while doing so.  You should also change the oil and inspect the air filter (should see light through a paper filter) or clean it (if it's foam).  Let me know what you find out if it still won't start.  Hope this helps.