Sounds to me like the first tech didn't finish the job, and you should be calling them up to remedy that for you. Any organization worth giving money to would consider this part of the original bill that you already paid.
But if not... Have you tried looking at the website for whatever company made your system? HP, Dell, Acer, etc... All have drivers for the downloading on their websites.
Original running program on my computer when purchased was windows vista. Im a graphic designer and my programs had issues, so my tech changed my system to xp. I'm trying to go wireless with an ethernet hook-up and there's no connection. Upon looking further into, I cannot find the driver. Is there one out there that I can download for free or will I need to pay a tech to fix this?