If someone promises to pay you for something via text messagw and they don't, is there anything you can do?

With the limited information, it would appear that this could be a breach of contract which requires an offer, acceptance, and consideration. You could speak with an attorney to obtain more information but likely this would fall into a small claims suit where attorney's are not allowed except in limited circumstances like an appeal. Therefore, you may want to research small claims in your area to pursue an action for breach of contract.