*First of all, i am trying to create a register system saved into textfile(not real system, i know its not safe to write into textfiles) Created the GUI and then i defined multiple functions which is Menu, register and submit. Submit function is nested and inside register function. The problem is when i nested the functions it doesn't write into textfiles, but when i delete the register function, it works. When i press register and write something in the Entry box, it didnt record to the text files, i have been scratching my head as to find what the error in my code is.

Edit: I now have put a picture to get better understanding. the blue window is main menu and its the mainloop and the yellow window is appearing when i click register button.*

Result Red:

Result for yellow: