L120 automatic won't start

How fast does it spin when you crank it ?
Try starting with one plug removed then the same with the other plug removed.
There are a couple of prime suspects. in no particular order.
Blocked air filter.
incorrect valve lash
low fuel level in float bowl
Excessive plug gap
non functional choke check this by pulling the choke on at the carb while the engine is running, If it 8 strokes or blows black smoke then choke is working.
Air leakage
blocked idle jet in cab.

Ok guys and gals. I took the plugs out got spark. Checked the hose going to carb. Gas pumped good. Took air filter off and seen a hose that comes from engine to the filter housing that wasn't connected. So I put back in. And it still wouldn't start.

So I got it running with gas in filter. Choked it out when at idle. Nothing changed. Rev'd it up and it started sputtering like any engine chokes out sounds. Started to have Lil black smoke. So I shut it off and tried it and it started. Not as quick as it should of but it did. So I ran it again doing the same thing with choke and repeated. It started. Idk if the choke was messed up or not but so far so good. I'll give it a Lil while and see if it'll start or not. I'll keep posted

The fuel pump has a one way valve in it, This valve holds fuel pressure to the carburetor when you turn the engine off so it starts easy the next time you start it. I have seen it where some dirt gets stuck in this one way valve and the engine will be hard to start after you turn it off. You are saying it runs just fine after it dose start is the reason I suggested the fuel pump not hold pressure.

So my mower has been starting but not as good as it was. It will crank for a couple times with choke on and wont start unless I rev it 1/4 way up. It will rum but takes a min to stop sputtering