Router Keeps on Disconnecting: Unable to find wireless connections

I have a router used for wireless to laptop and a wired connection for Playstation 3 and the desktop.
At first it worked fine but it would disconnect after around 30 minutes. I tried to contact online support and they suggested me to hard reset the router. I followed all the instructions given; reset the router and set up the connection again and now I wasn’t able to find the wireless connection.
I’ve tried many times to manually add a wireless connection to the laptop but it doesn’t work. Tried for an answer on Google for anything similar to my problem but found no answer. What is the possible solution for my problem?
