My son was struck by a drunk driver and lost his leg. The police report has no insurance info and my son was uninsured.

There is no question but that your son has a legal claim, the issue is whether there is any insurance coverage for his injuries. IF, and this would require substantial investigation, the person who owned the car which struck your son permitted, or could be legally proven to have permitted ,the operator of the car (the drunk driver) which struck your son to drive the car, there may be automobile insurance coverage. It may also be possible to bring a claim against the establishments who served liquor to the drunk driver, although, again, the question would be whether there is insurance coverage. 

It sounds like your son suffered some extremely serious injuries as a result of this accident. This isn't something you or she should be handling without an attorney; the stakes are simply too high. The lack of insurance on the police report, while not a good sign, does not necessarily mean that there isn't insurance you can go after. I recommend retaining an attorney to investigate into potential sources of recovery and to negotiate a settlement (or file suit, if necessary). Sorting out insurance isn't something I'd ever tell a person to do without a lawyer...especially not with injuries as serious as you've described. If you want to speak about this more in depth and don't already have an attorney, I'd be happy to speak with you and your son about his options. My number is (814) 452-6232.