Is there any natural way to grow back hair i pulled out while fiddling with it as a teen, 15+ years ago? or to make my thin hair fuller?

No, but Dr. can look: One's primary care doctor can check for medical causes. If none are found, then one can see a dermatologist, especially one specializing in hair restoration (some treatments: minoxidil, etc, ...). Medical causes may include: hormonal problems (low thyroid), seborrhea, alopecia areata, stressful illness. Other causes: genetic male/female pattern baldness, telogen effluvium.