Please Help - quite suddenly the web interface does not connect

Installation has been running fine for about a year. Linux on a Lenovo laptop.
Suddenly, without warning, the system became non-operational. Web interface would no longer connect. I could SSH to it.
I rebooted. No luck.
I powered down and back up. No luck.
I used openhabian-config to restore to the last working back up. No luck.
I am at a loss as to what to try. I am not much of a linux person but can follow directions.

Please help…I love my system and am lost without it…

Which browser are you using to the web interface?

Do you see any errors in that browser console when the UI fails to connect?

Do you see any errors in the openhab logs related to the UI when you start openhab?

After searching, I found this piece: Suddenly unable to access openHAB - #20 by rlkoshak

While I had not done an upgrade, it sounded similar enough where I followed the steps and put it to 3.4.5-1. It is again working. It is a mystery to me what had gone sideways but all is fine now. As always, thanks to all who support this fine tool.