Hi there,
Thanks for writing in! You can try connecting to your root WordPress directory via FTP and open the file wp-config.php and add following at the bottom:
define( 'WP_MEMORY_LIMIT', '256M' );
define( 'WP_MAX_MEMORY_LIMIT', '512M' );
Note that if your host limit the memory on server then it might not work. In that case ask your hosting provider to increase PHP memory limit.
You can find more information on http://codex.wordpress.org/Editing_wp-config.php#Increasing_memory_allocated_to_PHP.
Hope this helps.
Cheers!