When a contractor takes your money and disappears or botches the job, a documented demand is your first move.
Lay out what was agreed (scope, price, dates), what you paid, and exactly what's missing or defective. Attach the contract, invoices, texts, and photos. Demand that they complete the work or refund a specific amount by a deadline.
Many home-improvement contractors are licensed; in New York City, by the Department of Consumer and Worker Protection. Noting that you may file a licensing complaint, in addition to suing, gets attention. Keep it factual.
Sue in small claims (up to $10,000 in NYC) or civil court for larger amounts. You can seek what you paid for work not done, plus the cost to fix defective work, within the court's limits.
Generally yes. Keep proof of what you paid and what was delivered.
If they're licensed (e.g., NYC home-improvement contractors are licensed by DCWP), a licensing complaint can run alongside a lawsuit.
You can still demand a refund and sue. Paying in full doesn't waive your right to the work you were promised.