If you don’t remember your WiFi password and don’t have it written down anywhere, you can visit your router’s configuration pages and check it there. All you need is a computer that is connected to the network via wire or wireless.
If that computer runs Windows, open up command prompt, type ipconfig into the window and hit enter. A list of networking devices will come up. Find the networking device that you currently use to connect to your network (this could be a wireless adapter or an ethernet card). You’ll see a few IP addresses listed under that network card, and one of them will display your Default Gateway. This is your router’s IP address.
In this example my router’s IP is 192.168.2.1.
Mac OS X
If the computer connected to the network is a Mac, click the button in the upper task bar (up near the time and battery life, this is the icon that shows your WiFi signal strength) and click Open Network Preferences on the menu that appears. On the left side of the window that opens, you’ll see a list of all networking options on your Mac, and the one you’re using to connect to your network should have a green light and be selecred. Click Advanced in the main window, and look under the TCP/IP tab to find your router’s IP address.
Open up that computer’s internet browser and navigate to that IP address. For example, I would navigate to https://192.168.2.1 to get to my router’s configuration page.
You will be presented with a login page to access your router’s configuration. Every router is different, but default combinations are usually Administrator/Password, Admin/Admin, Admin/*Blank*. If you can’t access the configuration page check your router’s manual for the default username or password. Keep in mind that you may have set a custom password.
After you log in you can navigate to your wireless security options to set or check your WiFi password. As an example, on most Belkin routers you would navigate to the Wireless Security section on the sidebar. You can use that WiFi password to connect other devices to your network.
If you can’t access your router’s configuration page, you can reset the router to factory defaults (with no WiFi password) by unplugging your wireless router and holding down the reset button on the back while plugging your router in.