This question already has an answer here:
I've messed around with my network settings lately and I have no idea what I've done, but now my wifi doesn't seem to be working right. When I boot my system up I get the message
booting system without full network configuration
I tried following the guide here to reset my /etc/network/interfaces file, and now I get the same message at boot but my network manager doesn't even turn on when I login.
Any advice would be appreciated.