Please see the Headphone Jack FAQ for some details about jacks. The sound card itself is a chip that integrated onto the motherboard and cannot be replaced. Some models have separate jack circuit boards that can be replaced, but on the rest you have to replace the MB in order to replace the jacks. As far as I know the 1545 does not have a jack board. If anyone knows differently please let me know.
I would find a small screw with threads just barely wider than the hollow core of the shaft of the plug that is still in the jack. The shaft is hollow to allow the leads to pass through to the tip and ring. I would insert the screw into the opening of the shaft and turn the screw until it just catches -- that is until it starts to self-thread itself into the metal of the shaft -- then pull out the screw and shaft at the same time, using pliers to get a grip on the screw head. If the opening into the shaft has been bent or twisted closed, I would drill into it to create an opening.