Luckily, there's one keyboard shortcut that's saved me more times than I can admit: Ctrl+Shift+T (or Cmd+Shift+T on a Mac).

This will give a drop menu. From here you have two options: "Recently Opened" or "Reopen Last Closed Window." For "Recently Opened," you get a clearer breakdown of which tabs you had open, including ...

If you had multiple tabs, there will be an option under "Recently Opened," that says the name of the first site "and [Number] more tabs." Choose this. It will restore all tabs closed at the same time.