S46 TRACON Controller reported opening the sector with an aircraft on vectors with no radio contact established resulted in a failure to climb aircraft above the MVA and a CFTT event.

Narrative

Aircraft X was on approximately a 160 heading for TCM level at 030. I was opening the position and taking it from another controller. After settling into the position. It was time to base the aircraft. I turned them to a 250 heading and no response. Let it go a little further and tried again. With no response. By the second try they were approaching a 038 MVA. I reached out on guard twice; trying to turn them; no response. I had another aircraft try and reach out to them with a turn; no response. The aircraft was in the 038 MVA about a mile and a half. At this time they reached out to me; I turned and climbed them immediately to a heading of 280 and an altitude of 040. I then gave them a low altitude alert. I then found out that they were on 120.1. Which I didn't have keyed up. I didnt key it up because last I knew it was out. I was told it came back in service around three to four hours earlier. The past couple of weeks 120.1 has been going in and out of service. Also I should mention where the aircraft was; they should have been on 126.5 due to radio coverage. My recommendation is to make sure to brief pertinent information and make sure its acknowledged. It also recommended that you have aircraft on the right frequencies in the right places. On the pilot side I would recommend aircraft listening to guard frequencies. On my side; pay better attention to whats on the Information Display System. Even though we have plenty of problems with them being updated with current information.