[Kennym1986]

If my mower started yesterday but won't start today even though the battery isn't dead what could be wrong with it?

[eeseely]

From your description, you can crank the engine, so it sounds like a fuel problem.
If you left fuel in your tank over the winter, you could have water in your gas.
I would remove the spark plug, then dribble some good gas into the cylinder area; then
Put the spark plug back on and give it a crank.
If it starts briefly, then quits, you have a fuel issue.
Check your spark plug and clean or replace it if it has a lot of carbon on it.
Check for a spark by holding the spark plug wire about a 1/2 inch or less from
The top of the spark plug.

[ballengerb1]

I agree with most of the post above, it does sound like a fuel problem. If you check your spark it is more of a sure thing to pull the plug, reattach the wire and let the plug rest on the block and then turn the starter. You should see a very crisp blue spark, if not replace the plug after gapping. I would drain the tank and the carvb bowl and start with fresh fuel not stored over the winter. Add a small amount of carb cleaner like SeaFoam to the fuel. You may need to spray some starting fluid into the carb air intake to get it to fire.