wired connection disconnected in ubuntu 12.04

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http://askubuntu.com – i have a vaio vpceh26en laptop i have installed ubuntu 12.04 on a dual boot system but the problem is that it is not detecting lan & keep showing disconnected Bluetooth & wifi features are working fine but wired network is not being detected, Please give the complete coding for the solution as i don't know much about Commands in ubuntu (HowTos)