I had problems with my internet so a guy came out and put in a new modem and router. When he did so he changed my security type and gave me a new password. Problem is, I kept the same network name. So after about a week I did a system restore due to a bad file and the restore point was before I had the disc and the network changed. So I guess my network went back to no connectivity and it reads it as my old one I think? Because when I try to update with the new password it wont let me connect.
You need to connect the computer to the router using an ethernet cable. This bypasses wireless security.
You need to know the router's IP address (usually 192.168.0.1 typed into the address bar of your browser) and Username (usually admin) and the password (the default password will be in the instructions which came with the router -- download from maker's site if this has been lost).
Once into the router's user interface wireless security setting either note the passphrase or put in a new one.
Basically, most of what you need to know is in the manual for your router -- read it.