Alright try to plug in the ethernet cable and run
ip link show
sudo dhclient eth0 (Replace "eth0" with your interface name check with ip link)
If you see the interface, but its not managed run
sudo ip link set eth0 up
sudo dhclient eth0
(Once again use the interface from ip link)
Assuming you have network connection again run
sudo apt install --reinstall network-manager
sudo systemctl enable --now NetworkManager
If all that works run
sudo apt update
sudo apt full-upgrade
sudo apt autoremove
If that doesn't work run
journalctl -b -p 3 --no-pager
and tell me what that says