WPA passphrase is your wireless network password. It was given to you when you installed your wireless access point/router or other similar network device.
On a OS X platform, click Go from the Finder menu bar and select Utilities. Open the Keychain Access application and click Local Items. After that, select Passwords from the Category list, double-click the wireless network name and check the Shows password box. Also, you can find the password on the router configuration web page. Right-click the wireless icon from the menu bar and click Open Network Preferences. Go to Wi-Fi > Advanced > TCP/IP and locate the Router address. Open your web browser and enter the Router address. Type the username and password to open your router's configuration page and check the wireless settings option for the password. Sometimes it is called network key, passphrase, or wireless security key.
On a Windows operating system, click the wireless icon from the taskbar, right-click the wireless network name and select Properties. Press Show characters to see the wireless network password. If this doesn't work, download and install HP Print and Scan Doctor. Open the application, click Network option from the Menu and select Open Router Web Page. Type the username and password to open your router's configuration page and check the wireless settings option for the password.