woow congrates on wanting your curls back, going to be a long journey. bad new is that theres no quick way of "fixing" heat damaged hair, you just have to be super nice and gentle to it, cut the damage off and wait for the new stuff to grow out.
though somthing that could help is if you get rid of all sulfate and cones from your hair products, consider going CG as that will help you hair get back its curl n bounce.
for the heat damage that is there, i would try same hot oil treatments, i use a mixture of different oils each with somthing else that i no will do my hair good, i use a base of EVOO infused with rosemary, (rosemary helps with hair growth), i add honey, my hair loves it, then i add my other things, argan oil, (nothings better for hair repair) jojoba oil (newly bought want to try it) pumpkin seed oil (packed with vitamin A and E) tea tree, (great for keeping a healthy/clean scalp) i warm it up and applie it to damp hair, leave it in my hair for as long as you can, over night is perfect then wash it out with a gentle non sulfate poo.
also think about helping your hair from inside out, eatting plenty of fruit and veggies will help, drinking lots of water and plenty of exercise.
hope somthing here can help you

my hair: 3b, high porosity, high density and coarse hair (i think i finally figured that all out)
my hair loves conditioner only styling!
Oils and my own procuts are my hairs best friend
my hair goal length is bra strap length when curly.