Do I still have a case if we never signed a written contract?

You still have a case, but the absence of a signed written contract changes your legal timeline and, in one specific way, actually helps your position. California law requires a written contract for any home improvement work priced over $500, so if your contractor took a deposit and started work on a larger job without ever putting anything in writing, that missing contract is itself a separate violation you can point to, strengthening your overall claim rather than undermining it.

Without a written agreement, your underlying claim for breach is treated as arising from an oral contract instead, which under California Code of Civil Procedure section 339 gives you a two-year window to file suit, compared to the four years you'd have under section 337 with a written agreement. Texts, emails, a handwritten estimate, or even a witness who was present when terms were discussed can all help establish what was actually agreed to, even without a formal signed document.