A human being, alone in the desert, with no water and no food, will rapidly dehydrate and die within 5 days without water, and in about three weeks without food.
The only possible way to survive against a desert sun is to dig sleeping trenches perpendicular to the path of the sun during the early morning, sleep through the day, and travel at night. The trenches ensure that you are in shade all day except at the noon hour, thus minimizing your loss of water through sweat.
Water can be obtained by digging a solar still, but you need an oiled cloth, a bucket, and a straw of some sort to do so. The heat of the sun collects under the tarp, evaporating the ground moisture, which then condenses on the underside of the tarp, dripping down into the bucket.