Does it have a handle you have to hold while it is running that controls the throttle? If so, take off the cover and make sure the spring hasn't come loose that holds the throttle open. I was mowing a few weeks back in a pretty rough area around some azaleas and mine stopped abruptly. I had a cracked gas tank recently, so when I bought a new one, I put on new fuel line, new plug, new oil change, good spark, and I had sprayed a half o' can of ether into the carb throat. Took the cover off, and a vine had gotten under the cover and caused the throttle spring to come off. It started on the first pull after I reattached it.

Also, when you take the air filter off, have you pumped the little primer bulb to make sure you are getting gas? If not, you may have a hole in your fuel line, it may have come off, ect....

Sincerely, JD small engine repair.