Wordpress can go down and show a blank page, and the most common issues are with updates of plugins/theme files. Usually the white screens of death are common during updates as well. Since there will be multiple reasons for this issue, we will recommend you to go through the steps below
The most common cause for the white screen of death or blank page is during plugin update. To troubleshoot this problem, you can disable each plugin one by one until you get the pages load in your browser.
Log in to Server either via FTP or using cPanel.
Using FTP manager Go to Files or use File Manager in CPanel (For Cpanel servers)
Go to the directory where WordPress is installed and then go to wp-content/plugins directory.
Under this Plugin directory, you can see each plugin has its own folder. To disable a plugin, you need to rename its directory. (To disable wp-mail-smtp plugin, rename this folder to wp-mail-smtp.bak)
Then check whether the site is loading.
If you are still getting the blank page, keep disabling each plugin one by one until you find out the exact cause.
Please make sure to restore the plugin folders to their original names once the troubleshooting is done.
Changing to the default theme
Log in to Server either using FTP or cPanel.
Go to Files using FTP software or Files > File Manager if on Cpanel
Go to Wordpress installed directory and then go to wp-content/themes directory.
Make sure to note down the current theme.
Get the PHPMyAdmin URL from WPO or Click phpMyAdmin, in the Databases section of the cPanel.
6. Select corresponding database.
7. Click the wp_options table.
8. Locate the template and stylesheet rows, in the option_name column. The option_value settings in these rows contain the current theme.
9. Double-click the option_value setting and type the default theme name for the template and stylesheet .
10. Then check whether the site is loading.
Hopefully this helps.