What can I do if the person I worked for won't pay for a deck that I built?
Question Details: I was asked to stop building because they ran out of money.
You can sue them for the money. You would sue on two different grounds or bases:
1) Breach of contract, or the agreement (whether written or oral/unwritten) between you and them that you would build the deck and they would pay you for it. You did your part (were building the deck), so they are contractually obligated to do their part (pay).
2) Unjust enrichment: the law does not let someone accept services or work which they know were for pay without paying, since if they do, they have been "unjustly enriched."
If the amount is less than the small claims limit in your state, suing in small claims court is a fast, cost-effective option.