I have forgotten the security key to access my router

Solution
write it on the bottom or back of router where ever there is enough space for that info as you can't loose it unless you loose the router.
Do still you have devices connected to the router? If so, it might be possible to go into wifi settings on those devices and view the password. The password will typically just be shown as dots, but I think I've seen it where there's a "show password" checkbox you can click to reveal the password.

Alternatively, you can log into your router's web page and just change the security key there.

Edit: My bad, misread the OP. Thought you were looking for the wifi password. Did you ever change your router login info? It may still be the default login, which you can probably google for your router model. Often something like username: admin, password: password.
 
Check the router manual for the procedure to reset the router, the default password and username.

You probably need to turn on the router.
Press the reset button with the tip of a pen, then wait about ten seconds for it to reset itself.
 


EVERY router is password protected, every single one. You can't even turn them off, its absolutely required.


Just go to 192.168.0.1 or 192.168.1.1 to see for yourself?..

 
Sorry, my error. I was referring to the access to the router configuration. I had a password a few years ago but have forgotten it. I think the simplest thing would be just resetting the router. Thanks to those who answered. If I change the password again I will write it down and put it in a safe place and one that I will remember.
 


Yes, just reset it. And obviously, determine what the default username/password is before you do this.
Also, most routers default to Wireless Admin OFF, and Remote Admin OFF. SO be sure you are connected via a wire and not just WiFi.

This is a good thing.
 

Rubbish. I have multiple routers that can be used without a login password. AVM's FritzBox line, for example.