how to recover the router login password?

[michaelkenward]

You have a few options:

• see if the default password (on the device's label) still works
• dig deeper into your memory
• use password recovery, if you have set it up
• reset the thing to get back to the defaults

There is support for the R6120, including a manual, somewhere at the end of this link:

>>>> R6120 | Product | Support | NETGEAR <<<<

Check the sections Set Up Password Recovery and Factory Settings.