What is the best and fastest way to regrow hair that I pulled out of my head due to a bad habit?

Well here’s the deal. . . . I had a really bad habit of pulling out my hair every time I lay on the bed watching TV. This went on for about 3 months of pulling my hair about 4 years ago. Everyone keeps telling me that my hair grows back, but so far has not. Every time I blowdry my hair at the top of my head is flat on my head (and much less hair), while the back of my head is full of hair. So I ask you this. . . There is something that is out there that will work to regrow hair that I unfortunately pulled out? I have hair loss due to hereditary, but due to a bad habit. HELP PLEASE!