I'm 19 ys old.3 yrs ago I dyed & straightened my hair alot, it became dried & broke off. Its now growin slow & see lining of my scalp. Wat can grow it out?

Patience. Most often, the hair will grow back normally, if you've stopped the harsh treatments that damaged it. It takes months for injured follicles to recover and grow hair that is healthy and matches the length of your existing hair. Temporary use of a stimulating laser brush may speed the process somewhat, and make the existing hair stronger and healthier as well while you wait.
Over treatment. You over treated hair with too many chemicals as same time. Topical prescription steroids can decrease inflammation and allow regrowth. This will require a minimum of three months for hair to start regrowing.