The pen that Polly is talking about is probably your best first try. It is called a silver trace pen. They are available online or at Radio Shack here in the US. It runs about $11USD and has enough product to do a great number of repairs. You will need to secure one side of the ribbon cable with tape, glue or something, so you do not rip it any further. You will need a jewelers visor, loupe or stereo microscope to see what you are doing. On the unsecured side of the cable you need to clean the plastic away from the broken copper trace in the cable on either side of the break with an exact-o knife or similar, you can also use heat. You need to make sure you are only exposing the 1 trace. If you expose multiple traces you stand a chance of shorting them out. Patching 1 trace is going to be hard, but much easier that trying to patch in a new cable. I have done this with DS lite upper video cables. If you are patient and can see what you are doing it can be accomplished.