I can’t connect to Wi-Fi and I forgot my password for my computer

If you can't log in, you can't do anything until you fix that: https://support.apple.com/en-gb/HT202860

If you enabled the option to reset the Mac account password with an AppleID, you can connect your Mac to the internet in recovery mode via WiFi, or connect your Mac via Ethernet.

Otherwise, if your Mac is Intel, you can reset the device completely, but you will lose all personal files on your Mac.