I can't access my Home Assistant Green

I followed the quick start instructions and managed to configure several sensors. I was able to connect via my computer for two days, but on the third day I could no longer connect. What’s happening?
I need your help to determine what the problem is.

Hi, welcome to the forum!
Have you seen this: Troubleshooting installation problems - Home Assistant

Also, do you know whether your HA has a fixed IP address (or not)?