WordPress out of memory. This article describes some simple trouble shooting you can use to confirm the problem and get wordpress back up and running.

Symptoms

Wordpress site failes to load in browser and you get a white screen of death.

In the error logs, accessible via ftp or control panel you will see entries like this;

PHP Fatal error: Allowed memory size of x bytes exhausted (tried to allocate x bytes) in <path to file> on line x

In most cases the cause will be a faulty plugin or theme which may create an excessive number of entries in one or more table in your wordpress database.  If you open the database via the database webadmin built into your hosting control panel look at the number of entries for each table.  Below are some ballpark sizes for tables that have been know to cause issues.  If one of these tables is orders or magnitude larger its likely to be the cause.

To resolve the problem you can trim the junk entries from your database, but we reccomend you back up the table first just incase something goes wrong.  This should allow you to get wordpress back up and running.  Then you will have to identify which theme or more likey plugin is causing the problem and either update it, manually patch it or replace it with another plugin with simular functionality.