Add to the above list
Floating debris plugging the fuel outlet in the fuel tank.
Faulty carb solenoid
The best way to start is with a red inline spark tester
Hook it up & go mow
When the mower stops crank the engine and look at the tester
If it is flashing then the electrics are good & you have a fuel / valve problem .
When it starts again go mow but keep a can of carb cleaner with you.
The instant it stops squirt some cleaner down the carb & crank the engine.
Engine fires = fuel supply problem
Do the tests & get back if you need more help