You can perfectly scavenge a thin wire from old electronics or buy a length from a hardware store if what you broke is a mere wifi data/power cable. Do the cables connect to the antennas? If that is the case, then this quick fix will not work too well since you need special coaxial cables to ensure an interference-free wifi signal. Could you show us some photos of the cable that has been severed?
Either way, the fixes for this issue seem quite straightforward and I believe that with enough patience you will be able to get it to work without it being tethered to a smartphone.