First of all, check if your Omega is sitting correct in the expansion-dock. The pins should not be visible anymore if you press the omega on the Dock?!

@ venkata chandrasekhar nainala said:

After a few failed attempts to connect and update, I cant see the wifi any more and the led on the onion omega is not flashing.

To be able to help and give you advice we need more specific information. You have to look that you can connect over USB-serial cable and get more information from the boot process of the Omega. How to do so you find in onion.io/getstarted