Help with legal action: Tenants destroyed our house and may not show up at court?

If they don't show up you will get a default judgment against them, meaning that you have a court order requiring them to pay. Once you have that you can do things like garnish their wages and bank account, put a lien on any property (car, for example) until the judgment is paid. In the meantime get as much info as you can on where they live and what their assets are: Things like license # of car, where they work, etc.