Can't Connect to Internet After Upgrading from 12.04 to 14.04

I recently upgraded from 12.04 to 14.04, and unfortunately afterwards I couldn't connect to the internet, either via ethernet or wifi. It could detect the cable and wifi networks, but it just couldn't connect to them.

I can connect if I boot into recovery mode, and also if I boot using the Linux 3.5 kernel. The 3.13 and 3.16 kernels won't allow me to connect to the internet.

Here's my ifconfig from the 3.13 kernel:

https://gist.github.com/anonymous/c24eb9a165df1c199821

And here it is when it works successfully (booting in recovery mode on the 3.13 kernel):

https://gist.github.com/anonymous/22cb2f206673ab4b6c15

Any help would greatly appreciated!

Try this:

Switch on your computer.

Press and hold the Shift key, which will bring up the Grub menu.

Select the line which starts with --- Advanced options.

Select the line on the 3.13 kernel ending with --- recovery mode .

Your PC should display a menu with a number of options.

Select network - root or netroot.

In a terminal run:

  # mount -o remount, rw /
  # mount --all
  # rm -rf /etc/apt/sources.list.d/*.list
  # nano /etc/apt/sources.list

In the open file.

Delete the contents.

Paste the following:

deb http://us.archive.ubuntu.com/ubuntu/ trusty main restricted
deb http://us.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
deb http://us.archive.ubuntu.com/ubuntu/ trusty universe
deb http://us.archive.ubuntu.com/ubuntu/ trusty-updates universe
deb http://us.archive.ubuntu.com/ubuntu/ trusty multiverse
deb http://us.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
deb http://us.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse

deb http://security.ubuntu.com/ubuntu trusty-security main restricted
deb http://security.ubuntu.com/ubuntu trusty-security universe
deb http://security.ubuntu.com/ubuntu trusty-security multiverse
deb http://archive.canonical.com/ubuntu trusty partner
deb http://extras.ubuntu.com/ubuntu trusty main

Ctrl + O Save file. Ctrl + X Close nano.

And continue running:

# dpkg --configure -a   
# apt-get -f install
# apt-get -m install
# apt-get update
# apt-get dist-upgrade
# apt-get install --reinstall ubuntu-desktop
# apt-get autoremove
# apt-get clean
# reboot