I'm thinking he's probably still in the house somewhere. Hopefully he didn't get outside, its a bad time of year for that. Did you set up a basking areas inside the house, or only outside? If you don't have a couple set up in the house it would be a good idea to try it.
As mentioned previously if he's in the house he is likely alive. If outside things sound bleak.
However, here's a story of mine about one of a uromastyx I had. He was outside in the summer getting some sunshine. A girl near my house came over and dumped him out of the bin. I couldn't find him anywhere and eventually gave up after a few days of looking. About a month later I heard some scratching noises in my closet. I figured a mouse got in the house, however, it was the uromastyx!! The girl that dumped him out said he ran up the outside chiminy. The only way he could have gotten in the house was to run up the chiminy, getting into the attic area and then fell into the closet through the entry area in the closet.
So don't give up hope he may eventually turn up somewhere.