Ethernet- Device not managed after changing static ip

Question

I have changed the ethernet static ip to the default wi-fi local ip. This is so that my local and public services work after switching from a wireless connection to ethernet. At first, the solution was to change the interfaces to:

auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 192.168.1.wifiaddresshere
netmask 255.255.255.0
gateway 192.168.1.routeraddresshere

However, after a server restart, I can no longer connect via ethernet and the only way to do so is to revert interfaces back to its original state, i. e.:

auto lo
iface lo inet loopback

Any suggestions as to how I can fix this issue?

Solution

Open terminal :

gksudo gedit /etc/NetworkManager/NetworkManager.conf 

You will see :

[ifupdown]
managed=false

change it to true

Restart network manager

sudo service network-manger restart

Comments

[user251124]

gdksudo? I have never heard of that command. Linux suggests gksudo. PS: I use Ubuntu 13.10

[user251124]

thanks, gksudo command worked. Thank you! The internet is working as supposed to.

[user251124]

Replied slightly to early. Although the ethernet connection is "working", it is shown to be called ifupdown (eth0) which is not supposed to be the name of the connection. Additionally, the connection only works on a local level, it does not connect to the internet. I can ping servers like 8.8.8.8 and others, however, I can't actually go on them, ie: through firefox or to download from them, ie: sourceforge. When I type in the ip address into the url bar, I get no response, it just tries connecting indefinitely.

[nux]

ok my friend dont forget to mark the question as an answer