Q: My airlock blew off during a violent ferment. Is my beer now ruined?
A: Once in a great while I get a question such as this.
Usually it is accompanied by vivid detail of how a ceiling or wall also got plastered.
The beer is fine.
When a ferment is going this wildly it is pushing off so much CO2 that no other microrganisms can fall in to contaminate it.
Take the airlock and stopper, clean them, and reinstall. Be happy - the beer Gods have smiled down upon you with violent ferment.
They don't choose just anyone ya know.