Have lost or deleted an invoice.. any way if retrieving it

Hi sales-boatybits-, thanks for posting on the Community

You can view recently entered transactions by clicking the magnifying glass on the top-right toolbar in QuickBooks. 

If the transaction doesn't show here, select Advanced search on the bottom of the tab and adjust the filters on the following screen to find the type of data you want.

You can also use the audit log (Settings wheel > Audit log) to view all account activity, to check if the invoice was deleted. Please note, you'll need to sign in as an admin to access the audit log. Ask your primary admin if you don’t see it.