Sometimes when editing .php files you will make a mistake and end up breaking your theme or sometimes you might upload a theme that is old and out of date or is just too problematic and it needs to be switched back to the twenty ten default theme.
Some times the following error may occur.
Here is an easy way to switch to the twenty ten default theme using PHPMyAdmin.
Step 1
Go into your cPanel and look for the Databases section and click on the phpmyadmin link.
Step 2
Select the database where your WordPress is stored.
Step 3