Fatal error: Allowed memory size of 268435456 bytes exhausted

Hi.. I recently got this msg on my site while going thru settings of the plugin SuperSlider-login:

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 261900 bytes) in /home/content/78/9634878/html/wp-includes/script-loader.php on line 487

I m not sure what triggered this msg..I have tried the following:
1. If you have access to your PHP.ini file, change the line in PHP.ini
If your line shows 32M try 64M:
memory_limit = 128M ; Maximum amount of memory a script may consume (128MB)

2. If you don’t have access to PHP.ini try adding this to an .htaccess file:
php_value memory_limit 128M

3. Try adding this line to your wp-config.php file:
Increasing memory allocated to PHP
define(‘WP_MEMORY_LIMIT’, ‘128M’);

But no change..
Can anyone please help???