Unhappy IMEI Changed , No Network

Friends I'm in a trouble.

I was using Cynogenmod 11 and that time my Network was fine ... as soon as I restored my stock Rom (4.1.2) , I lost my network ... when I make calls ... a pop-up message appears "Not Registered on Network" . Manually Selecting the network also doesn't work. In Phone status ... it show NO SERVICE

My Previous IMEI Number was 353**************** and now it has changed to 0049*****************

I'm not able to make calls or recieve it ... PLEASE HELP