The WPA2 passphrase is stored in the router's administrator page. It might also be on the bottom or side of the router. If the passphrase was changed from the default one, then the easiest option is to get into the router's administrator page and find it there. The third option is to use a wireless surveillance tool to crack the passphrase.
In order to retrieve a WPA2 passphrase from the router's administrator page, first plug a computer directly into the router via an Ethernet cord. The user should use the router's IP address or login page to access the router. This is frequently http://192.168.1.1, but certain brands may have specific pages. Then the user enters the admin name and password to access the page. An individual looks for the wireless tab on the front page and click on that. Then they click on the security tab and look for the passphrase field. They then check the option to show the passphrase and write it down for future use.
If the router cannot be accessed due to a lost admin name and password, the router must then be reset. The router is reset by holding the reset button on the back for about 20 seconds. Then they follow the basic install instructions that initially came with the router.