Then you'll have to contact official EA support: https://help.ea.com/
I doubt this will help, but... In Origin, upper left corner - Origin/Reload My Games. Maybe that option is there for a reason..
Already did that, the game still doesn't appears --'
Are you sure you logged in with the same credentials (email / password) you used when you first installed Origin and the ME3 Digital Deluxe Edition?
Other than that we cannot help you in account related issues, only official EA support can: https://help.ea.com/ You might have to switch your country to United States at the bottom of the page for all contact options to be available.
I'm sure I'm logged in with the same credencials that I used to buy the game, when I look at my order history, I can see the game, the Mass Effect 1 and Dragon Age: Origins that I bought together with it.
