Carb will not prime

I believe this mower has a primer ball on the carb. I presume you have pushed it (at least the three times mentioned in the manual (and you can or can't feel whether it's picking up any gas). If it's not picking up gas when pushed, check for obstruction or kinks in the fuel line from the fuel tank to the carb.

Have you tried removing the air filter, squirting a little fuel into the throat of the carb, replacing the air filter and then trying to start it? Sometimes that's all they need to get primed. If it starts, then dies, try it one more time. If that doesn't work, I'd look for an air leak in the fuel line (it may be drawing air instead of fuel). When using this method (you may alternatively squirt a little fuel directly into the spark plug hole and replace the spark plug), if the engine fails to fire at all, you're probably looking at no spark. Just be careful when spilling fuel! Do this outside!