Can’t login to wp-login.php – returns blank page

if you have ruled out a plugin or theme issue

1. Try adding this line to your wp-config.php file:
define('WP_MEMORY_LIMIT', '64M');

2. If you have access to your PHP.ini file, change the line in PHP.ini
If your line shows 32M try 64M:
memory_limit = 64M ; Maximum amount of memory a script may consume (64MB)

3. If you don't have access to PHP.ini try adding this to an .htaccess file:
php_value memory_limit 64M

4. Talk to your host.

thanks for the reply. Unfortunately none of these helped.

adding the line to .htaccess produced a 500 Internal Error page.

I have also removed some plugins via FTP – but again, no luck.
The site is now back up but I still can’t access admin and new users trying to register can’t access admin either.

Any other leads?

This is solved now. Simple ideas always go a long way – I deactivated certain plugins I thought might cause issues and bingo. I was even able to reinstall all plugins I deactivated as precaution.

Thanks for your help.