Hello there.
I leveled up my goblin DK and completed my herritage armor quest. After that I purchased race change and switch from goblin to orc. I noticed that I have no herritage armor set for him now. Will I be able to get orc herritage armor quest somewhere or do I need to lvl up another orc character?
Server: Drak’Thul
char name: Podrazimír
Thank you in advance for answering, you guys do great job 
I’m not exactly sure what you are asking.
Only Goblins can wear Goblin Heritage Armor, just as only Night Elves canwear Night Elf Heritage.
If you had a Goblin character, got Goblin Heritage, and then race-changed that to an Orc, that character can’t wear the Goblin Heritage anymore, because it is not a Goblin.
But if you make a new Goblin, that Goblin can wear it.
If you now want to get the Orc Heritage Armor on that character, you should be able to:
To be eligible for a core race’s Heritage Armor you must have a character of the respective race at level 50 and at least one level 60 character on the Battle.net account. Once all the criteria are met, you may start the quest line for your Heritage Armor.
Using a Character Boost, Race Change, or Faction Change no longer disqualifies the character from doing Heritage Armor quests.
I am aware that now he as orc cannot wear goblin herritage armor. My question is if he already completed goblin HA questline (when he was goblin) is he now able to also complete orc HA questline? Because currently I cannot see that quest anywhere.
Ahhh! Sorry, I see the problem now.
Check your character Completed Quests with Wowhead Quest Tracker or an addon like BTWQuests.
I am pretty sure these quests will be marked as Complete, which would mean you can’t do them again.
Yeah. Thats what I am afraid of 
Luckily I still have orc toon at lvl 1 so there is till hope
EDIT: I did as you say and on Wowhead Quest tracker I noticed that now after race change he is not exalted with Orgrimmar, which is one of prerequisities. Thanks for your help