You've got the right guy to help you recover the deleted transaction.
Yes, you can recover deleted transaction, and I just want to clarify what type of transaction it is, to ensure I provide you the right steps to recover it. Since you mentioned that you were reviewing expenses, is this a downloaded bank transaction?
If it is, and you excluded it from the For Review tab in the Banking page, we can recover it by going to the Excluded tab to recover it. Let me walk you through the steps:
Click Banking in the left navigation bar.
Click the Excluded tab.
Locate the transaction and click Undo under the Action column.
After clicking Undo, let's go back to the For Review tab and check if you can see the transaction.
However, if this was a transaction already recorded in QuickBooks, then you'll need recreate it manually to recover the transaction. Here's an article that'll help you recreate the expense: