If you have already lost the hair on your head and have active bald spots there are really only two options to deal with the problem.  This is not to say that there are only a few things to do if you are just having hair thinning problems.  In fact, hair thinning is much easier to deal with than total hair loss.  There are FDA approved drugs like Finasteride and Minoxidil which are both affective at slowing hair loss and keeping the hair you have.  But this is not the case once all the hair on an area has fallen out.

At that point you have two options. You can get a hair transplant surgery and trasplant hair follicles from one area of the scalp to the bald area.  Or you can get a non-surgical hair replacement system also known as a toupee or hair piece.  Although less expensive than surgery, a hair system does require replacement every six months to a year and there are other issues with them.