The users do witness a lot of problems when they try to reset Asus Router rt n66u, however hard resetting your Asus Router is not difficult.
All you need to do is to turn the router off
Then press and hold the WPS button
And then turn on the router. Now. The power light is on
Then you must keep holding the WPS button.
Then, you should release the WPS button just after the power LED lights to start flashing
Then flashing will stop, and the router will reboot automatically.
By following the above-stated steps, you can simply find out the ways to fix it.