...It's possibly not starting just because it's wet from all the water which has leaked out. Be worth mucking around with it cos if it's just a hose off that'll only be pennies to fix.
If it's the water pump then that'll be money, likewise if it's the head gasket.
If the radiator itself has a hole in it (can happen... rust, or sharp stones flying up etc.) then that'll also be money as it's quite a big part.
Assuming you've not got a friendly mechanic who'll come over & have a quick butchers, then my advice would be either...
1) Let it dry out completely (use a rag inside the engine compartment, especially on the electrics, and leave it standing - overnight if you can) then try starting it again. Even if there's no water in it, it should fire & run. don't let it run for long though.
If it still doesn't go, then it may be the gasket gone & you may have water in the oil & sheet like that which can be nightmarish. Cetainly it's non-trivial.
or
2) Keep lobbing water in till you find where it's leaking from. Hopefully you'll see a loose or busted hose & it'll be job done.
What sort of car & what age is it?