I logged onto Ubuntu to realize that my Ethernet connection is not connected. It has worked fine until now. Any help would be appreciated. Also, I'm using Realtek Ethernet.
Open a Terminal with Ctrl+Alt+T and type:
You should get something like this:
Notice how I have an inet addr defined. If you do not have an IP address then something is wrong, most likely it is a DHCP problem.
Can you ping 192.168.1.1 or ping 10.0.0.1? (Most likely your router's LAN ip is one of those)
If you can ping one of those, then you can see your router and you are not getting a IP from the router. This could be either your router DHCP not configured/setup or your system not requesting an IP from the router.
That is if you have a router.
In the Terminal type:
and add this two lines in the bottom:
Save the file and now, to restart your network, on a new Terminal type:
Finally, use the below commands enable/disable eth0: