Increasing the WordPress Memory Limit

Method 1

Edit your wp-config.php file and enter something like:

define('WP_MEMORY_LIMIT','512M');

http://codex.wordpress.org/Editing_wp-config.php#Increasing_memory_allocated_to_PHP

Method 2

In you have access to your PHP ini file, change the line in PHP.ini as below

memory_limit = 512M;

Method 3

If you don’t have access to PHP.ini try adding this to an .htaccess file

php_value memory_limit 512M

If none of those works for you its best to contact your web host and seek their assistance as they would know more about your website hosting space.