DHCP fail error using Mega and ENC28j60

I have used Arduino Mega and ENC28J60. Connections (Vcc - 5V, SO- 50, SI - 51, SCK- 52, CS-53) I have used Ethercard library. Initially it worked well but after few days it shows me on serial monitor as shown below..

DHCP failed My IP : 0.0.0.0 GW IP :0.0.0.0 DNS IP : 0.0.0.0

REQ

usually its conected when i did first and i got the IP add in serial monitor, but now i get this. I have checked all the connections properly. Please find me a solution for this .

Check your network configuration and cabling. Replace the network cable from the Arduino to the next network device you checked explicitly to be in a working state (by attaching the PC to it for example).

If you want us to help you, you have to post a detailed plan of how your network is organized, showing all connections. Post a as complete as possible configuration description of your router (I guess the DHCP server is running there). Also post a link to the actual hardware you use (I doubt you use the ENC28J60 on a self built board, if I'm wrong and you did this, post the schematics of the board). The post the complete code of your sketch (don't forget the code tags!).