There's a case [1] of an old guy who fell into coal fire and regrew his hair. He basically regenerated his skin and his hair. Microneedling [2] has been used successfully to regrow hair.
Methods like minoxidil and finasteride work well as preventative measures. However, it has been shown that with advanced balding there are skin changes (e.g. fibrosis), so you have to regenerate your skin first if you are visibly balding and then use preventative methods to not lose your hair.
There are some encouraging results [3] with people using skin regeneration methods like microneedling together with minoxidil & finasteride.