ethernet is not working


I have installed Jet-pack 2.0 and CUDA 6.5 using an Ethernet cable from a host PC and it was working properly. suddenly, I am unable to connect my Jetson tk1 with the network any more, how to fix this?
(please provide me a detailed instructions since I am a beginner in this stuffs).

Thanks in advanced.

From the Jetson, what is the output of “ifconfig”?

It gives me the “IP adress” for eth0

Some eth0 addresses are for failed DHCP (often something close to a 169.x.x.x address). Does this address work for you?