...power on one line coming in. If you have a multimeter and you are comfortable removing the electrical panel cover, you can test power on each of the main 120V wires coming in. At the top of the panel, you should see a large allen screw where each main wire attaches to the panel. If only one of these reads ~120V, then you know the issue is somewhere between the power company and your electrical panel.

If you have 120V on both main wires, then the issue is either in your panel, or somewhere in the distribution wiring in your house. I had a similar issue about two years ago, and it turned out my main breaker was going bad. It was a "snap-in" breaker rather than "bolt-in" type, and over time it had loosened up to the point that sometimes it would make contact with both bus bars that energize the branch circuit breakers, but sometimes it would only contact one bus bar and I'd lose half of my circuits. Apparently this is a well-known issue with older Murray panels, so if your panel has a Murray label on it, this could be your issue.

Good luck...if you aren't comfortable with electricity, I'd recommend calling the power company first so they can determine if the issue is on their side of the panel, which they should do at no cost.
[Post edited by MP4VT2004 at 10/27/2020 08:35AM]