How successful you will be depends on what exactly you broke. If you can slide the ribbon end in but the problem is that it won't stay because you broke the clamp slide, then a piece of cardboard or plastic might help. The slide pushes the contacts of the cable against contacts in the connector. Sugru is interesting stuff but isn't what you want here, because you want to apply some modest amount of force against the backside of the ribbon end. Maybe a bit of sugru will hold the whole thing in place once you have the ribbon end wedged in.
Try it with the cardboard first. You want to slide it in between the backside of the ribbon (without the exposed contacts) and the shell of the connector.