Today everyone is expected to remember lots of passwords. The ones you use frequently are rarely forgotten, but the router password might not be one of them.
So what can you do if you happen to forget both the wireless and the configuration panel passwords?
Well, it's quite simple, really. Most if not all wireless routers have a small reset button on the back side. Use a paper clip or a pencil and press and hold this button until the router LED's starts blinking - usually around 5-10 seconds.
Your router will now be restored to factory settings, and you may login to the configuration panel using the default username and password. These are found in the router documentation, but if you cannot find them or are simply lazy, try one of the following common combinations:
In worst case, google your router brand and model followed by 'default password'.
Mind that you will probably need to login to the configuration page using a network cable (not wirelessly) since the wireless mode is often disabled per default when the router is reset to factory settings.
You should now be able to login and enable Wireless mode and set a new wireless key, WEP or WPA