Apologize, refund the money and move on? Hire someone to help me finish it? A third alternative is to reduce the scope to something you can finish. 37signals a

Apologize, refund the money and move on? Hire someone to help me finish it? A third alternative is to reduce the scope to something you can finish. 37signals advocates compromising on scope but never on deadline, and I agree. Any of those options would be fine. What's important is that you keep the client in the loop so that they can find another developer if they need to, before the project is 2 months late with no end in sight. As a corollary, be upfront about your skillset, and don't take jobs you know you can't finish. As with anything, lying will bite you in the ass.