I AM LOSING THE WILL TO LIVE!! MY EXTENDER WON'T ACCEPT THE NEW ROUTER'S PASSWORD! PLEASE HEEEEEELP!

I've been dealing with this ALL DAY! Aaaaaarrrrggghhhhhh..... :-(
My Extender won't accept my new Router's Password. 
I have looked it up on the Community Board and this seems a common problem. 
There was a "solution" whereby you find your Extender's IP Address by "looking it up on your Router's List of Addresses". 
How do you do that!!?? 
This was supposed to be simple. 
Then there's another video I've watched (of many!) where you go on Netgear's Genie. 
You can't access that s a webpage, can you? 
I've downloaded the App onto my Mobile Phone (iPhone 7 Plus), but it STILL asks you to provide your Password (i.e. the Router's password), which IT DOESN@T ACCEPT. 
I've tried using the "default password" which is "password" but it DOESN'T WORK. 
OM flippin' Gaaaaaaawd!! PLEASE HEEEEEEEEELP!! 
ps. I don't speak "tech". 
Thank you so much! 
Tony
tg.segui@gmail.com