Cannot login AC1200/R6220 Router

That's a pity, but without some useful details it is anybody's guess as to what is going on.

 

How do I log in to my NETGEAR wireless router? | Answer | NETGEAR Support

 

and this:

 

If you cannot login to your router | Answer | NETGEAR Support

 

If you need more help, you can help people to help you by providing the information suggested in this forum's header:

 

Subject (Include model number and brief summary)
Model (Recommended - Helps the community give the best answers)
Body (Include additional detail including model version, firmware, OS and environment where relevant.)

They are there for a good reason.