I'm going bald because of head lice. I have two patches and I'm thinning all over. How can I get my hair to grow back quickly?

If you are balding due to head lice, the best way to treat it is to treat the cause. See a doctor.  You cannot grow back the hair quickly.

If you're thinning from lice, you need to treat the lice. Once the lice is treated and you stop itching hair will grow back.  However, if you have hair loss from another condition (in addition to the head lice), hair might not grow back as easily.  Be sure to see your physician to determine exactly how many reasons for hair loss you might have. It's possible to have 2, 3 or even  4 reasons for hair loss in the same person. 

First, of course, find out why you have head lice and get it treated properly. Then wait out the normal hair cycle telogen phase with runs about 6 months and see if it grows back.