Mobile network not displayed after I rooted my samsung galaxy 10.1 tablet

I have a Samsung galaxy 10.1 tablet (GT-P7500) with android version 3.1. I upgraded the android to 4.0.4 (the latest one available). It was rooted but I guess I've modified something since it always used to show "permission denied" for superuser requests. So I rooted the tablet. When I did, the tablet didn't reboot by itself. Someone suggested that I wipe all data. So I did it and now the tablet reboots well, but it isn't showing the mobile networks options when I go to Settings > About device > Wireless & Networks. I am not getting the 3G network either. I want my tablet to get the mobile network again and I want to upgrade it to android version 4.0.4.