Hi lynnfromaptos!
It sounds like Wi-Fi isn't working on your Mac, and I'm happy to help. From your mention of Thunderbolt Bridge, it sounds like you are looking at the Network pane in System Preferences. On the left hand side of that window, you should see a white column that lists your current network services; this is normally where Wi-Fi would be listed, and likely where you currently see Thunderbolt Bridge. At the bottom of that column, you should see a plus sign, a minus sign, and an "action" gear. If you click on the plus sign, it should give you the option to add a new network service, including Wi-Fi (make sure you select the Wi-Fi interface on the drop down that pops up). What may have happened is that the minus button was accidentally clicked while Wi-Fi was highlighted, which would then remove that service.
If for any reason that doesn't work to restore your Wi-Fi option, you should also be able to create an entirely new Network location, with a brand new set of default settings for each service. You can find more information about that in the following article:
How to use network locations on your Mac - Apple Support
Cheers!