won't connect to wifi

Restart your router/modem/

Startup in Safe mode. https://support.apple.com/en-gb/HT201262

    To leave Safe Mode, choose “Restart” at the bottom.

    Quote:

     Safe mode prevents your Mac from loading certain software when it starts up, including login items, 

     system extensions not required by macOS,

     and fonts not installed by macOS. It  also does a basic check of your startup disk, 

     similar to using First Aid in Disk Utility. 

     And it deletes some system caches, including font caches and the kernel cache, 

     which will be created again automatically as needed.

Try suggestions given in this article.

https://support.apple.com/guide/mac-help/if-you-cant-connect-to-a-wi-fi-network-on-mac-mchlp1185/mac

whites the status of your Wi-Fi as shown on the System preferences > Network pane?