Can melanocytes damaged/destroyed by trauma recover/regenerate?

Your question does not permit anything but a general answer. As a rule, loss of pigmentation due to damage to melanocytes secondary to inflammation--whether from traumatic injury (or inflammatory diseases,, infection, and surgery)-- tends to be permanent. The damaged region typically heals as an off-white or ivory white scar. Repigmentation is possible when melanocytes have not been entirely destroyed by the prior inflammation or trauma. Having said that, I have found that the use of medical microneedling coupled with the application of topical tyrosine or bimatoprost to be helpful in certain circumstances for promoting some degree of repigmentation even in older scars where it seems clear that there is an absence of functioning melanocytes. Although, I do not think this has been studied, it is possible that microneedling may autotransplant functioning melanocytes from surrounding normal skin into the damaged area. You would do well to consult with a board certified aesthetic physician with experience and expertise in scar treatments. Best of luck to you.