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. Then find your ethernet/wireless adapter in the list and look for the Default Gateway listed under that. This is your router’s IP address.
In this example my router’s IP is 192.168.2.1.
If the computer connected to the network is a Mac, open up Network Preferences (either from the system preferences or the AirPort icon in your status bar), click Advanced, 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 http://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 holding down the reset button during startup.