The 3 basics. 1. Spark. 2. Fuel. 3 Air. Always start with checking for spark. Then fuel. Air last.
If this has been coming on gradually, could be burned points, and just got worse. If you have at least good spark, and no start, Shut the fuel off above the sediment bowl, then check the sediment bowl, and screen above it, if it still has one. If that is good, remove the fuel line where it goes into the carb. Open the fuel, and check for good flow to there. If you're good there, remove the elbow the fuel line attaches to going into the carb. There should be a fine mesh screen filter on that el. These will plug over time, and gradually slow fuel delivery, to the point of plugging. Some spray carb. cleaner, and low air pressure from a blow gun will clean them up.
If beyond that, a good carb. cleaning. Be sure and remove the brass discharge nozzle, and make sure the small cross drilled holes are open. Some will say put a carb. kit in it, but all but one of the 14 gasser's I have, they only needed a good clean up.
With the ethanol laced gas we have now, it sure causes a lot of problems if they set much.