A blank white page usually means a PHP error. Try these in order.

1. Disable plugins: rename the wp-content/plugins folder via File Manager (article 105) to deactivate all plugins. If the site returns, rename it back and re-enable plugins one by one to find the culprit.
2. Switch to a default theme: rename your active theme's folder to force WordPress onto a default theme.
3. Increase memory: raise the WordPress memory limit (article 97).
4. Enable debugging: set WP_DEBUG to true in wp-config.php to see the actual error.

Note: Always back up before editing files. The error logs in cPanel (Metrics > Errors) often point straight to the cause.