How to fix Wp-admin redirects to wp-login.php which goes to 404 not found page

I had several web sites where when I tried to login with wp-admin it used to redirect to wp-login.php which gave a 404 not found error I did all I could some of the things which I did were

Completely reinstalled the wordpress with fresh files

Upgraded my sqil database

changed the site urls in the database

Completly rewrote the wordpress .htaccess text

Nothing worked finally a video posted on you tube gave a solution which was much easier and worked perfectly

All I had to do is add the following code in .htaccess file at the end and it worked perfectly

<Files wp-login.php>
Order Deny,Allow
Deny from all
Allow from all
</Files>

This was it this worked and I was able to fix this untiring error that had kept me from posting to my web sites.

You can change the .htaccess file via ftp or via cpanel file manages.