Not registerd on network

Hi guys

You are probably sick of hearing this problem but I have had it and I have tried to scour the internet and I cannot find a solution to my problem.
Basically I have not used my Samsung Galaxy note 2 GT-N7100 for 6 months or so and I decided to use it and to use a new rom. Now after I installed it I could not call anyone or text anyone nor could anyone else call me or text me. However, the internet was working which was strange but again I got the same error message "not registered on network. I tried to install another rom in the hope that the problem would be sorted out but this time I cannot get the mobile data or the wifi to work either. The main problem is the "not registered to network.

The first rom I installed was the latest Hawkish extreme rom and the second one was Android Revolution HD by Mike1986 if it makes it easier to help me. I will still be searching on the internet but if someone can help me that would be grateful and much appreciated.

Thanks in advance

Thanks for the reply.

Right before bothering to read the reply I decided to download omega jellybean 4.3 and guess what, no imei number but I flashedkit kat back in and it was buisness as usual. emergency calls only. Right when I get back home I shall try what you told me, but one question as a n00n and I do apolagise, where is this efs folder?

Thanks for the reply, I almost lost my rag yesterday with this phone!

Thanks