Finding your WiFi network password - Windows only

Your Wi-Fi network password maybe able to be recovered if you forget it. You will need a Windows computer connected to your network and an additional device such as phone, tablet or additional computer. 

1. On a Windows computer connected to your Wi-Fi network, do one of the following, depending on the version of Windows running on the computer:

   • In Windows 10, select the Start button , then select Settings>Network & Internet>Status  >Network and Sharing Center.

   • In Windows 8.1 or 7, search for Network and wireless communications, and then select Network and Sharing Center in the list of results.
     To find out which version of Windows is installed on your computer, see What Windows operating system is my computer running?

2. In the Network and Sharing Center, next to Connections, select the name of the relevant Wi-Fi network.

3. Under Wi-Fi Mode, select Wireless Properties.

4. Under Wireless Network Properties, select the Security tab , and then select the Show characters check box .
   The Wi-Fi network's password is displayed in the network's security key box.

On another Windows computer or device, connect to the Wi-Fi network as usual, and enter the Wi-Fi password when prompted.For more information about connecting to a Wi-Fi network on a Windows 10 computer, see Connecting to the Internet.

Source:Finding the Wi-Fi network password in Windows