Ubuntu, network interface and problens

I was very upset today, at the moment.
My ubuntu, more precisely the gnome, messed the whole network interface and now I can no longer get access to wired connection…
It seems any more windows viruses than a problem for gnome / ubuntu.
hooooooowever, I’ll show what I tried to do and the procedures for configuring my network interface. Hope that helps someone, because I did not help much. only in the end I hace success.
for you to view the network interfaces on your computer:
sudo = to superuser
sudo ifconfig-a
For you to edit network interfaces:
sudo gedit / etc / network / interfaces
here you will open the file interfaces .. gedit is the editor of textual, you replace it with vi, vim, etc …
in my case I put it in the file,
# The loopback network interface
auto lo

iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet static
address 192 168 143 169
or to set up direct ip do this:
sudo ifconfig eth0 netmask
remembering that eth0 is my network interface is eth0,
I thought I could set up so I went on board and was like, friends here at work said I was right,
hoooooowever, to no avail ..
Then I edited the file sudo gedit / etc / network / interfaces
and left it like this:

auto lo
iface lo inet loopback
# The primary network interface
auto eth0

ready, wired connection back to work …
why have stopped working is still a mystery ..
I’m going to find out why .. but I hope it could be help…I almost lost a day trying to find out to solve it..