admin password retrieve R9000 Nighthawk

Does the recovery page come up from the router at the routers web page?

https://kb.netgear.com/24220/How-do-I-recover-my-NETGEAR-admin-password-using-the-password-recovery-feature

 

If password recovery doesn't work (or wasn't setup), then you'd need to factory reset to get back in. 

Push and hold reset for 7-15 seconds while its powered on. Then follow the install guide to reinstall.