Short answer: Credit score damage, penalty fees, possible default and forced sale. Call bank before missing payment.
The bank will contact you immediately. One missed payment affects your credit score. Multiple missed payments lead to penalty fees, higher rates, and eventually default. Default means the bank can force a sale of your house. If you know you will miss a payment, call the bank before it happens. They often have hardship programs.
Missed Payment: $3,327
Penalty Fee: $50
Credit Impact: Reported to credit agencies
After Three Missed: Default proceedings begin
Solution: Call bank immediately, request hardship assistance