Assuming you are running some recent version of Windows ...
- While connected to the router, select Run from the Start button on the task bar. This will open a Run dialog box.
- Type in
cmd and press the Enter key. This will open a black command line screen.
- Type in
IPCONFIG and press the Enter key. This will generate a short report.
- Look at the data under wireless adapter if the computer is using a wireless connection or look under Ethernet adapter if you are using a wired connection.
- You are looking for a line labeled "Default gateway" followed by four numbers separated by periods. Note that entire number.
- Click the "X" in the top right corner to close the command screen.
- Start your web browser on the computer and put the gateway IP address in the address bar in the form of
http://nnn.nnn.nnn.nnn , where nnn.nnn.nnn.nnn is the gateway address.
- You should then be prompted for a user name and password. This is not the same as the WPA passphrase. If you do not recall ever setting a password for the router, try
admin for the user name and leaving the password blank.
- Once you are logged into the router, find the wireless configuration page(s) and see if they show the passphrase as plain text.