So any computer connected to the switch that is connected to the AP still works? At least this helps us understand that the connection to the your business is fine. Is only 1 computer connected through the AP? If others, do they have the same problem? Open up command prompt and do ipconfig /all, what's the IP address you get is it 0.0.0.0 or 169.xxx.xxx.xxx?
Do you know any other people in the neighborhood that have a wireless connection? You can try changing the channel or frequency on the AP, used a wired computer to configured it.