I don't own Dragon age: Inquisituin apparently

I have read this about three times, and while it maybe that I am just tired, but I can't really understand what it is you are saying exactly.

I get, you bought the game, played it and it is gone.  You have Origin Acess and can play the game, but can't check the achievements??

Most common cause of games going missing...logging into the wrong Origin account.

If you have Origin Access, you should have access to the game and achievements, I think, but I don't have access, so I am not 100% sure.  If you check your account history in the Origin app, it should show you all purchases and such.  If you have Access unlocking Deluxe game, it MAY be hiding the "standard" version if that is what you purchased.  If you still have issues, I would contact EAHelp.com and chat with an advisor, as this is a player to player help forum, and there aren't any EA people here except for some community managers.

What I am saying is that I cannot play the game because as the title says it's not in my games library, it has to put it simply vanished.

Sorry, but no one here can do anything for you. The AHQ is for player-to-player  self-help and game play discussions.

We're all just fellow gamers here, doin' the best we can...

The only people who can assist with account, log-on, purchase, entitlement, or refund issues are the EA Game Advisors.

You can reach them at help.ea.com/contact-us.

Provide the Game, Issue ("Topic"), Platform, and select "Contact Us" (not "AHQ").

ProTips:
1. Be at your gaming rig.
2. Be logged-on to your EA/Origin account (unless that's the problem, obviously.)
3. Be able to spend 10-30 minutes "on hold" before reaching someone.

Good Luck!  🤓