Damaged curly hair

6th grade was when I found out there was such thing as a hair straightener and my oh my did I go ballistic cuz one stupid girl made a rude comment about my natural hair. So 6- 8 th grade I used that thing every 2-3 Days and I’m cringing just typing this ( I found out in 7th grade there was such thing as heat protectant😬😬 )

Anyways I’ve pretty much completely stopped straightening my hair and my hair used to by super curly and now it’s just frizzy and curly/ wavy and I want to get it back to how it was and make it healthy at the same time.

Any products I should try? Also with frizz!!!!

Also I just recently heard about s thing like twisting ur hair to “train” it to be curly or something. If anyone knows anymore Info about that can I let me know cuz that seems interesting. I’ll do some research too though. Thanks guys!!