The White screen of death is probably caused by an error in your theme or a plugin. If you or your host has recently updated php or if you just updated WordPress, it could be due to an older theme with outdated code.
1. Log into your FTP account (you can also use file manager if you have access to this in your control panel but FTP is the preferred method).
Rename the plugins directory in wp-content to something like plugins.x – Detailed instructions
2.Set debug to true in wp-config file Detailed Instructions
Try your admin page again. If you still get the white screen of death,
3. Using FTP (IMPORTANT) download your current/active theme to a backup folder. Try deleting the active theme from the themes directory in wp-content. (back it up first by copying it to your local pc). This should cause WordPress to revert to the default theme. This may or may not work, so just copy your current theme back if necessary.
4. If you are now able to view your admin page you should look for errors in the theme and check for an update. If that doesn’t resolve the issue, contact the theme developer to fix them, hire a developer or try a different theme.
If you don’t see any issues with the theme, your issue is probably a plugin issue.
5. Create a new, empty wp-content/plugins directory using FTP. Start adding your plugins from plugins.x to the plugins directory and activating them one by one until you find the problem plugin. Contact the developer, look for an update or a replacement.
7. Still not fixed? Hire a professional.