Keep his deposit & last month’s rent, I hope you have this but if you have not better do this next time. Just get a form called residential lease agreement for your new tenant. Get to work finding a new tenant ASAP, and sue for any rent money you lose by having it vacant that isn’t covered by his deposit. Remember, the bank does not accept excuses for nonpayment/breach of contract (no matter how sad or creative) and neither should you. You are running a business, not a charity! If you need the forms for this. There is a site which contains all type of forms. I think it’s ezlandlordforms.com
Hope this helps.