If you're worried, hit the keg with some CO2 every day. It's heavier than air so it will tend to blanket the beer. Take some aluminum foil or a heavy baggie and wrap the valve to prevent much air from coming in.
And keep spare keg parts on hand for the future. This will happen again. If keg parts fail, disassemble and clean. If they still fail, replace them. Don't be cheap. One ruined batch Is worth more than a pile of spare parts.