Electrical question

Not really a century home question but maybe. I do live in a 105 year old house but the electric is updated. I’ve always found this sub to be the most helpful so thought I’d try here.

I will consult with an electrician but just looking for any insight.

I recently bought a new (old) light fixture. It needed rewired and I figured I know some basics, and I could attempt. I removed the previous fixture I had hanging and tried my newly rewired new (old) fixture. Nothing. The voltage tester was going off all along the wire up to the socket. I took everything apart, tried again and nothing. Tried a few other things and same thing. I removed the socket and hooked the ends up to the previous fixture and still nothing. I tried a different wire and still nothing.

At some point along the way, I was no longer picking up voltage anywhere. A light that shares the same breaker works. I tried hooking up the fixture I originally had hanging, that worked an hour before, and nothing. I knew there was a chance I’d fail at rewiring the fixture, but I didn’t expected to fail this bad.

What did I do? Any ideas of something else I could try? I’m thinking of making sure the wires at the switch didn’t magically get disconnected (they look fine though) and thought of cutting a few inches of the house wire and trying new ends.