Accidentally closed a tab which you need get back to? Edge Insider makes it simple to recover what you were doing.
To reopen a recently closed tab, right-click any tab on the tab strip. From the context menu which appears, click the "Reopen closed tab" link. You can also use the Ctrl+Shift+T keyboard shortcut.
This method only restores a single tab. It always picks the most recent one from your history of closed tabs.
If the tab you want to reopen isn't your most recently-closed one, click the "..." menu button in the top-right of Edge's interface. Expand the "History" menu. This flyout includes a "Recently closed" panel which displays all the recently closed tabs retained in Edge's history. Click a tab to instantly return to it.
You'll need to use the regular History interface if your target tab doesn't appear in the "Recently closed" menu. Click "..." > History > Manage history, or press Ctrl+H, to open the history screen. Here you can browse a complete chronological history of the tabs you've opened within Edge.
Finally, you can make Edge automatically restore your tabs when you open the browser. This should be on by default but to check, open Edge's settings ("..." > Settings). Click the "On startup" page and select the "Continue where you left off" option. Edge will now automatically restore your tabs whenever it is opened.