It sounds as if there is a good chance you got water in the capacitor or more likely, the coil secondary - never put water near anything British, I thought everyone knew that. If either coil or capacitor is the problem, your best chance of saving it is to dry it out very gently, by blowing warm dry air over it for a long time. It must not get hot during this process, or you'll finish it off completely. Realistically there is a good chance it is ruined anyway. If you tried to start it with the coil wet, it will have flashed-over inside the secondary winding, and that may have created carbon trails that now can't be removed.
It is more common for capacitors to fail than coils, and they are easier to get, so trying another capacitor is the first thing to do. If that doesn't help, when you have dried the coil out, if you take it to a mower shop they may be able to test it for you. If the mower shops can't test it, low voltage testing with a resistance meter is not a reliable test for this kind of problem, but if you have access to a megger, that will give you some kind of indication. It tests at about 500V, but the coil runs at around 10,000-20,000V, so the repair shop's proper test is the only authoritative way to find out. If it fails low voltage or megger tests, it is garbage, but if it passes them it may still be garbage.
If another capacitor doesn't help, and your coil is given a clean bill of health on a proper high voltage test, tell us about it and we can work through some less likely possibilities.
