Brain damage doesn’t give you free gifts. What happens sometimes is that in losing one ability you free up some space for another, which is why blind people, for instance, are more likely to have perfect pitch.
But creative talent requires both some innate ability and a fair bit of work. Having perfect pitch won’t allow you to magically play an instrument, that takes practice and discipline. The great majority of good musicians don’t have perfect pitch, what they have is good relative pitch developed by putting in a lot of work. Yes, good musicians were born with innate abilities, but every single one of them also worked like a bastard to hone those abilities.
Good musicians make it seem effortless: speaking as someone who can play several instruments to a high standard, I can tell you there’s a heck of a lot of obsessive work behind every apparently effortless performance.
Some people are born with innate talents, but without developing those talents, you’re never going to be able use them. There’s no kind of brain damage that will give you musical skills without any effort on your part. At best you’d be able to consciously hear subtleties in music that most people never notice.