Flex cable to Volume button was cut, now I cannot hear ringer.

I was adding a LED mod to my iPhone 4 and in the process of taking off the Plate with five screws at the top which under it has the connector boards. I split the flex cable to the the volume buttons on the side. Now of course the buttons and switch does not work. But I noticed when I get a Call the ringer does not sound. I can play music but ringer does not work. Tell me what to fix next please