What legal actions can I take against someone who I payed up front that is no longer contacting me?

About 2 and a half months ago I posted an ad on Craigslist to hire someone to develop an iPhone app for me, we talked back and fourth over phone and email and he said he could do it, I decided to hire him and pay him everything upfront ($5,500) instead of weekly as it would save me money in the long run. I met him in person, had him sign a contract I got offline and edited to fit what we needed, and payed him with a money order. Now two months later I haven't heard from him, he had told me that his number might cut off because he was switching carriers, and it has but he still has my email and hasn't responded in 24 hours. I've got his old number, email, picture of his drivers license, and signed contract. If he continues not to reply to my emails what legal action can or should I take? I don't know if he skipped town, is just ignoring me, or even if he's still alive (he told me he had some medical issues).

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