Solved my problem, but sharing
I have a Swann security camera system with wired cameras. It has worked fine for me for years. I'm a single woman living on a nice, quiet dead-end street with a cul-de-sac, and it's almost always very quiet at night. The main use of my cameras is to see if the outside cats have shown up for breakfast, or to see who's at my door when somebody rings my doorbell after ignoring the "No Soliciting" sign they walked past to get to it.
Well, this morning I had no video at all. All I saw was "Video Loss". I checked playback and saw that it all stopped around 10 p.m. last night. I checked all of the connections, and then it occurred to me that maybe the power supply for the actual cameras had failed. I thought I might have to order one, but then remembered that I had another power cord because I had replaced the dvr a few years ago.
And that's what it was! I am relieved. Last night there was some faint "booming" where I lived, and then a big boom that shook my house. I had thought to myself that it sounded like someone landed on my roof, and I had creepy thoughts that someone was walking around up there. But I shook that off and went to bed. I'm sure the "booming" was coming from Fort Carson, which is around 40 miles away. It can get pretty loud at times.
Just sharing in case this weird scenario happens to someone else.