I'm trying to make a button like a switch, so if I click the disable button it will disable the "Button" (that works). And if I press it again, it will enable it again.

I tried things like if, else but didn't get it to work. Here's an example:

from tkinter import *
fenster = Tk()
fenster.title("Window")

def switch():
    b1["state"] = DISABLED

#--Buttons
b1=Button(fenster, text="Button")
b1.config(height = 5, width = 7)
b1.grid(row=0, column=0)    

b2 = Button(text="disable", command=switch)
b2.grid(row=0,column=1)

fenster.mainloop()

A Tkinter Button has three states : active, normal, disabled.

You set the state option to disabled to gray out the button and make it unresponsive. It has the value active when the mouse is over it and the default is normal.

Using this you can check for the state of the button and take the required action. Here is the working code.

from tkinter import *

fenster = Tk()
fenster.title("Window")

def switch():
    if b1["state"] == "normal":
        b1["state"] = "disabled"
        b2["text"] = "enable"
    else:
        b1["state"] = "normal"
        b2["text"] = "disable"

#--Buttons
b1 = Button(fenster, text="Button", height=5, width=7)
b1.grid(row=0, column=0)    

b2 = Button(text="disable", command=switch)
b2.grid(row=0, column=1)

fenster.mainloop()