I can't pull the pull cord on my briggs & straton

Hi,
Remove the spark plug to see if you have liquid in the cylinder. Also, see if you can turn the engine by the blade, carefully!
Could be hydraulically locked or locked for another reason.
Peace,
Clarke

Agreed but also check your oil level to see if your crankcase is now totally filled with oil and gas. If you carb has been leaking fuel over the winter months the fuel will settle down in the oil sump, can't get the piston to move if there is no air space left in the crank.