The calm playbook for a blank white screen

Sometimes a site shows nothing but white. It feels like the end of the world. It almost never is. Usually a plugin or theme misbehaved.

1. Don't panic, and don't make more changes.
2. Try the admin area, yoursite.com/wp-admin. If it loads, you're in luck.
3. Go to Plugins and deactivate the one you changed most recently. Check the site.
4. Still blank? Deactivate all plugins at once, then reactivate them one by one, checking after each.
5. If a recent theme change is the culprit, switch temporarily to a default theme.
6. If you can't even reach wp-admin, ask your host's support to rename the plugins folder for you.

In plain words: a white screen is almost always one bad plugin, turn them off, then back on one at a time to catch it.