If the stripped end looks rather burnt, that is indeed your problem. I can't tell you where it connects to C, but I can tell you that that is the return for all your devices. If it's laying on the floor, then somehow it used to be connected... If it looks burnt, overheated, or the insulation is melted, then it carried too much current and that current might have also run to ground and blown that connection too before it blew off.
You may get your devices back, but I would still be very wary of your 7 pin connector and the wires leading to where the fault occured.
