You can activate your WordPress theme from within the database. This is helpful if you can't access WordPress due to an issue with your theme.

Log into phpMyAdmin.

Click on the database you want to manage.

Click on the wp_options table.

Under the option_name column, locate the template entry. You may need to navigate beyond the first page of entries.

Click Edit next to the template entry. In the option_value column, change the value to the name of your theme. The new value must be the same as your theme's folder name. To save, click Go.

Click Edit next to the stylesheet entry. In the option_value column, change the value to the name of your theme (or child theme, if you've previously created one). The new value must be the same as your theme's folder name(ex. twentyseventeen). To save, click Go.