The easiest option to solve these problems in Wordpress CMS are as follows

  1. Deactivating the plugins that are unused can free up some PHP memory.

Methods for increasing the amount of PHP memory limit:

a. If you have access to your PHP.ini file, change the line in PHP.ini
If your line shows 32M try 128M:
memory_limit = 128M ; Maximum amount of memory a script may consume (128MB)

b. If you don't have access to PHP.ini try adding this to an .htaccess file:
php_value memory_limit 128M

c. Try adding this line to your wp-config.php file:

Increasing memory allocated to PHP
define('WP_MEMORY_LIMIT', '128M');

d. Talk to your webhosting webmaster.