How do I restore my lost wireless internet network?

I had a wireless internet network Desktop/Laptop using a Netgear Router but no longer can connect to the internet on the laptop, a friend did the installation and was working fine. I had to disconnect the desktop for awhile and after reinstalling it again I lost the wireless connection to the laptop and do not know what to do to restore it, it was originally installed by a friend but he is no longer available and I do not have the money to hire a technician. Could anyone tell me what I need to do, step by step, I am a computer illiterate person, please help I'm disabled and without my laptop wireless internet I am lost.