Can't access wp-admin

Common reasons:

1. Memory Limit issue: Solution below.

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

b . 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)

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

d. Read this. https://wordpress.org/support/topic/how-do-i-fix-fatal-error-allowed-memory-size-of-94371840-bytes-exhausted?replies=14

2. Changed of the Admin URL.

See this forum for that http://forum.ait-pro.com/forums/topic/protect-login-page-from-brute-force-login-attacks/

3. Plug ins issue.

You may need to access the File Manager. Go to wp-contents and rename the plugins folder into plugins.back