arcanerain
Need some advice. I contacted my interviewer assigned three days ago via email and haven't heard from him. Sent out another email today.
Do you think I should drop him a message/call on phone?
Or should I contact the adcom?
First off - congrats on your interview invite
Most likely an honest mistake on his side - an email that got lost in all other emails. I got my interviewer's work email so I presume he gets many many emails every day. (i.e. don't get worried he's not interested in interviewing you - pretty much all alum are keen to contribute in every way possible!)
If I were in your situation, I'd probably send a brief update note to the adcom person to keep him/her in the loop - so it doesn't seem as you are the one delaying the interview process. Just say that you have reached out and still have not managed to get hold of him and that you will try again by calling him directly (I'd probably call the person directly tomorrow or so). Most likely the adcom will also nudge the interviewer to get in touch.
Hope it works out! and hope your interview will go well