Why did the internet stop working on ubuntu?

Question

linux

After trying to set up a pppoe connection in ubuntu 12 (I set it up).
When I restarted the computer, the Internet stopped connecting. Resumed the connection through the router, restarted the computer again and that's it! - In ubuntu, the icon of Internet connections (wi-fi, lan, vpn, etc.) disappeared at the top right, now the Internet does not work at all.
Help, please.

Answer 1

PPPoE, probably, configured through the console? But why? NM has been able to configure PPPoE for a long time.
To fix it (unless, of course, you didn’t touch anything else, and it’s completely impossible to understand from the question whether it was touched or not), you need to bring the /etc/network/interfaces file to the form:

auto lo
iface lo inet loopback

And... And restart your computer.