Also released with Version 2.5, the WP_MEMORY_LIMIT option allows you to specify the maximum amount of memory that can be consumed by PHP. This setting may be necessary in the event you receive a message such as "Allowed memory size of xxxxxx bytes exhausted".
->Please open wp-config.php file and add below code to increase the memory size
/*Increase PHP Memory to 64MB*/
define( 'WP_MEMORY_LIMIT', '64M' );
/*Increase PHP Memory to 96MB*/
define( 'WP_MEMORY_LIMIT', '96M' );
/*When in the administration area, the memory can be increased or decreased from the WP_MEMORY_LIMIT by definingWP_MAX_MEMORY_LIMIT.*/
define( 'WP_MAX_MEMORY_LIMIT', '256M' );
