NoMethodError in controller that has methods defined - ruby-on-rails

Question

I finished implementing and testing a controller, then switched back and forth between Git branches and did some merges here and there, etc.
Now I'm unable to use the methods I've defined for the controller, and also very confused, as I'm getting NoMethodError when trying to call them.
Added an edit and solution at the end of the post.
Using Rails version 5.2.3 -
Here I've got my controller defined: app/controllers/paypal_access_token_controller.rb:
class PaypalAccessTokenController < ApplicationController
before_action :authenticate_admin!, only: [:show]
def njurf
puts "#######################"
puts "why can't i call these methods dangit"
puts "#######################"
end
def show
# doesn't really matter
end
def update
# doesn't really matter either
# no syntax errors, I promise
end
end
I'd like the update method to be called when I start the Rails application.
I added PaypalAccessToken.update() to the file config/environments/development.rb - this worked.
Now that I've implemented stuff in other seemingly unrelated parts of the application, I can't call on methods from this controller anymore.
I removed the line from config/environments/development.rb so that I could run the Rails console and added the njurf method to the controller. From the console, I tried calling PaypalAccessTokenController.njurf, and PaypalAccessTokenController.update, but both give me the bespoke NoMethodError.
Here's some proof of concept
Loading development environment (Rails 5.2.3)
irb(main):001:0> PaypalAccessTokenController.update
Traceback (most recent call last):
1: from (irb):1
NoMethodError (undefined method `update' for PaypalAccessTokenController:Class)
irb(main):002:0> PaypalAccessTokenController.update()
Traceback (most recent call last):
1: from (irb):2
NoMethodError (undefined method `update' for PaypalAccessTokenController:Class)
irb(main):003:0> PaypalAccessTokenController.njurf()
Traceback (most recent call last):
1: from (irb):3
NoMethodError (undefined method `njurf' for PaypalAccessTokenController:Class)
So the controller class exists, at least, but I don't know why I'm getting this error - nor do I know how to go about fixing it.
Any help would be appreciated.
edit: This controller only had routes for the show method. I removed this route when I had implemented and tested the update method, because I no longer needed/wanted these methods to be accessible via URLs.
This is what made the methods inaccessible from console.
solution: Either I leave in a route to one of the controller's methods - or, like Ricky Spanish and amit_saxena pointed out below, properly declare the methods as class methods.
Thanks for the replies

Answer 1

You can call it, when you define it with self
def self.njurf
puts "#######################"
puts "why can't i call these methods dangit"
puts "#######################"
end
PaypalAccessTokenController.njurf
#######################
why can't i call these methods dangit
#######################
=> nil

Answer 2

It might look strange, but are you sure you have defined the proper resources on routes?

Answer 3

You cannot access controller methods like that from console as they aren't class methods. You can instead try this:
PaypalAccessTokenController.new.update
but that doesn't mean it's going to work (it probably needs params to work on), but you will not get a NoMethodError. Most probably you messed something in your routes file. You can check the routes using:
bundle exec rake routes
which will tell you exactly which route points to which controller#action and should give you some pointers about what the problem is. Paste the relevant routes here is you are unable to figure it out. Also pay attention to HTTP method (GET/POST/PATCH). You might be using a GET instead of PATCH and getting the error as a result.