All I get is a white screen when I try to log into the back-end of my Wordpress sites. All of my sites are working fine from the front, but if I cannot log in, I can't make any posts. I can't change any themes, or add any plugins. It's just a white screen.
Recently, I tried installing a theme, but I deleted the theme from my FTP servers and was completely fine. I have already tried turning off all the plugins and all of the themes, but to no avail. I think there is something else wrong.