I'm trying to get every music track unlocked and i have to go under mort'ton to get to the shade catacombs, my question is do i have to rebuild temple to get key to go under mort"ton?

Yep! You need to repair the temple so you can bless some olive oil. Then use that on some logs to make a pyre log. Next you need to kill shades to get their remains. Use the logs and the shade remains on the funeral pyres to burn the shade remains. A fairly common reward from doing that is the very key you need to get inside those tombs.

thanks man, really appreciate it

Well actually you can buy sacred oil on the grand exchange and bypass the minigame completely. But since you need to go to mort'ton anyway, you might as well bring a few materials and repair it a little instead, since you only need 1 key anyway.