It's hard to grow back you've lost..I have a full head of hair with a slightly receding hairline at the crowns, however, my little brother who is only 24 is nearly bald. He's been taking a few supplements after I showed him this hair loss forum, it's been about a year and he's seen some growth but nothing dramatic.
http://www.hairlosshelp.com/FORUMS/
http://www.hairlosstalk.com/interact/
Hair transplantation is an option, but it's expensive and a very drawn out painful process. A lot of people think you get the transplants and that's it you have a head of hair. There is a long healing process, failures, unnatural looking grafts, infection, scars, etc.
Post op pictures that can be found in the forums above
http://www.hairlosshelp.com/forums/a...1467&forumid=1
http://www.hairlosshelp.com/forums/a...3400&forumid=1