Guild Wars 2

I bought Heart of Thorns and when I go to my mastery tab it says locked. I didnt get anything at lvl 80 showing the quest Torn From the Sky, which it says I need to start unlocking my masteries.

Start the quest from your hero panel, then you will have a green prompt on the map to guide you.

Torn from the sky is not the first mission, it’s the second. The first is Rally to Maguuma, and you start it in the Silverwastes near red fort. The masteries unlock after you finish Rally to Maguuma, iirc.