Messy telephone wires behind jack

I got rid of the (real) old phone jacks in my old post-war building apartment by simply cutting off the phone wires from the jack and hiding those wires. Of course, I thought of reconnecting the wires to a new jack, but this was not feasible since the wires were so messy (50+ wires) so there was no way to do it. Honestly I don't even know if the phone jacks were in working condition previously. Question: Is it possible (just in case) if I want to rewire the phone system in the future? I understand I might need to hire someone (may be from Verizon?) to do it again. Is this going to be an expensive project? I have noted all locations of the hidden jacks in my floor plan.