Small Engines (Lawn Mowers, etc.): Lawn mower starts and dies, time gas, carburator

Question
Please forgive me for I'm in no way knowledgeable of lawn mowers, just a single Mom trying to fix her lawn mower on a small budget.  My son was mowing today, said he had a hard time getting the mower started, had to prime 6 or 7 times instead of 3 or 4.  He stopped the mower to move something.  When he went to restart it, it starts for about 20 seconds and then dies.  I did try to remove the gas cap as another article suggested but couldn't get the mower to start at all at that point.  It now seems completely dead.  I know the mower has oil and gas, I've replace the spark plug and I'm unsure what I need to do past that.  I definitely have not done anything past these basics.  Could you give me a starting point so I can try to fix it?  I'd also appreciate any knowledge of diagrams on parts so I can understand how to get to whatever the issue is.  I'm willing to try anything once....lol.  It's a Craftsman 6.0.  Thank you!

Answer
 Hello Debbie:

 It Sounds like the Carburator Requires a Good Cleaning and Rebuilding. Over time Gas Forms a Varnish Inside the Carburator and Stops the Main Jet from Functioning Properly. Being Hard to Start is a Good Indication of this, as is the Runs a Few Seconds and Quits. If you send me the Model Number Off of the Engine and Off the Frame I can Assist you Better. Hope this Helps. Let me know what Happens, Please.

 Good Luck

 Respectfully

 John