1) Increase memory in your config file.
Locate your wp-config.php file. This file is located in the root of your WordPress installation. Edit the file and enter something like:
It’s important to set WordPress memory because WordPress memory can be different from the server. You need to set this regardless of server memory settings
2) Increase memory in your php.ini file
If you have access to your PHP.ini file, change the line in PHP.ini. If your line shows 32M try 64M, 96M or 128M:
memory_limit = 96M;
Maximum amount of memory a script may consume (96MB)
3) Increase memory in your .htaccess file
If you don’t have access to PHP.ini try adding this to a .htaccess file:
php_value memory_limit 96M
4) Talk to your host
If none of the above works then talk to your host. They should be able to help you increase your memory limit.