If you want to increase WordPress memory limit, you can use one of the following methods:

1. Increasing memory limit through “wp-config.php”:
Please go to root directory of WordPress and open “wp-config.php”. Then find the line that has “WP_DEBUG” and add the following code after it:

define('WP_MEMORY_LIMIT', '128M');

2. Increasing memory limit through “PHP.ini”:

Please go to root directory of WordPress installation ( where wp-config.php file is located ) and look for “php.ini” file ( if it’s not there, create a new one ) and add the following code:

memory_limit = 128M

3. Increasing memory limit through .htaccess file.

Some servers accept “.htaccess” file modification. Please go to root directory of WordPress installation ( where wp-config.php file is located ). Usually you will find that file, but if you couldn’t, please read following stackoverflow question
You can add following code to .htaccess file:

php_value memory_limit 128M

4. If none of those methods worked, you should contact your host administrator to increase memory limit.