You can increase memory_limit on your server in several ways (back up any files you edit to be able to restore them):
1. Try adding this line to your wp-config.php file:
2. If you have access to your PHP.ini file, change the line in PHP.ini
If your line shows 32M, change it to 128M:
memory_limit = 128M ; Maximum amount of memory a script may consume (128MB)
3. If you don't have access to PHP.ini try adding this to an .htaccess file:
php_value memory_limit 128M
4. If all the methods mentioned above do not help, create a file called "php.ini" in the "wp-admin" folder of wordpress install.
Add the following text to the file;
memory_limit = 256M ;
5. Contact your hosting provider.