I have an I phone 3GS 16MB. Apparently it is "Jailbroken" (whatever that means). my grandson tried to upgrade it from 4.1? to 6.1.3 and when he connected it to I tunes it jammed the phone which now says " there is no SIM card in the phone" (there is) and now I cannot use the phone at all. Would appreciate some help please.
In essence, jailbreaking your iPhone means freeing it from the limitations imposed on it by your carrier, whether that's AT&T or Verizon, and Apple. You install a software application on your computer, and then transfer it to your iPhone, where it "breaks open" the iPhone’s file system to allow you to modify it.
That being said I think you will have to restore it to original. Your carrier will not help and void your warranty if you jailbreak it.