Fatal error: Call to undefined function register_sidebar2()

While attempting to create a new sidebar (sidebar2) in Theme Functions (functions.php), i received this message “Fatal error: Call to undefined function register_sidebar2()” when updated. I saved the original code format in case this happened, but when pasting it back into the code box, the same error message is displayed. I checked several similar posts on this forum, and the solution seems to be that by uploading a fresh version on my theme, it will overwrite the error and return to its original form. My problem is that ANYWHERE i click, i am taken to the error page. Can you anyone please help see what I am doing wrong???