It is a frightening scenario. Your WordPress blog has been running just fine for years, but you finally decided to try out some new themes. One of the themes you try goes crazy and completely brings down your WordPress site. Instead of the blog you worked so hard to create, you are left with a white page and a single-line error.
First of all, do not panic. While it seems quite awful, you can fix this situation. There are a few reasons why a theme or plugin might knock out service on your blog, but we will cover those later. First, you need to get it working again. If the culprit is your new theme, the easiest solution is to FTP into your server and delete the theme directory found in “wp-content/themes.” Once it is gone, WordPress will detect its absence and allow you to login to “wp-admin” and change the theme back to something that works.
For plugins you need to do the same thing only with a different directory. Find the plugins directory associated with your rogue plugin in “wp-content/plugins” and remove it. You should now be able to login to WordPress, and it will inform you that the plugin is missing and has therefore been deactivated. If WordPress still shows remnants of the plugin, make sure you remove it completely. If you installed multiple plugins and do not know which one caused the mess, you can use a database method to disable all your plugins at once.
Some themes cause WordPress to choke because they require other components that you have not installed. Often times this is because the theme is part of a set that requires a particular theme engine. If you install the theme engine first, it will work. For plugins, the problems are wide-ranging. Some are just incompatible with your version. Others may have problems with settings on your web server. You may need to consult the plugin creator for more help.