Help with a Check Session Error

Hello!

I got this error today and was trying to fix it:

An uncaught Exception was encountered
Type: Error
Message: Call to undefined function checkSession()
Filename: /home4/cultured/public_html/application/controllers/Dashboard.php
Line Number: 14
Backtrace:
File: /home4/cultured/public_html/index.php
Line: 315
Function: require_once

For just this line of code within a controller:
 checkSession();

I changed up the login/register code for my site and wonder if that has anything to do with it. This controller is from a chatbot system I implemented a few weeks ago. Tried to do a session destroy but that didnt help. I cant get to my main dashboard because of this error. How to fix this if possible?

,
Mekaboo