How can i stop or treat a receding hairline? female. 40

Start with your MD: Have a physical by your regular physician, who can check things like thyroid levels, hormone levels, and vitamin status. S/he may consider rogaine (minoxidil) or other prescription medications to help stop hair loss or even regrow some. Last option is microfollicular hair transplantation, or microdot tattooing. Be careful about the latter as hair color changes, but tattoos do not!