Wont start as in its "locked up" ,or just spins over without firing?..
It's not uncommon for many small engines with gravity feed carbs to get the crankcase filled with gas if they were stored with gas in the tank and no fuel shut off valve,or you forget to turn off the gas..the needle & seat valve in the carb can let gas overflow if they stick open and it'll siphon into the crankcase..
I've seen a few lawn tractors do this,to the point the engine hydro-locks and bends or breaks the die cast connecting rod..
Depending how much gas was in the oil and how long it was run will be a factor as to how much damage was done...
You may get away with just changing the oil,and making sure the carb doesn't let the gas get in the crankcase again..I'd add a shut off valve if it never came with any..
I'd also make sure no mice are living in the engine's tinwork,if it was stored somewhere that mice could get at it too,their nest will make it overheat and score the piston & cylinder after a short time...
The engines can be rebuilt as long as the rod didin't break and take out part of the block or other internal parts like the bottom of the cylinder...usually its cheaper to just buy a short block or a whole engine,some online stores have certain ones for sale very cheap..
