I have been following the videos on youtube, to learn how to make new themes for the 5.7
I totally like the way they are made, simple and easy to follow.

I was at the part that i was going to make a page_theme.php file. I was removing the Urbanic theme in the Pages and Themes, so i could install it again, for the page_theme.php, could take effect.

But after that i can not get into the Pages and Themes again. I get the following error message on the screen, as you can see in the attached file.

I have tried to delete the, page_theme.php page again, but still i can not get into the Pages and Themes