ICCID No sim After Jailbreak

Iphone 3GS
Re- jail broke my phone after trying to do an update as was only only running Firmware 4.1, thought I had only gone to 6.0 but looks like 6.1.3 and now I cant pich up a signal, am on 3 network. On check ing phone it says ICCID: No sim.
Any ideas, afraid not a techie so as simple as poss would be good.