If you know something from your account was deleted here’s how you can check.
Activity Log
When you go Settings - Log of deleted items you are able to see if someone has recently deleted anything. You can see the user who deleted it, time and date, module. It doesn’t have a lot of information but it will say what was deleted, so let’s say Invoice, Customer, User etc. That will be written in the Module column.
Deleted invoices shown
You can filter out deleted invoices. Sales - Invoices - Deleted invoices shown, when you choose that filter and click on Show then you can see if any invoices have been deleted. You are not able to open them but you can see the Invoice number and date
Deleted documents shown
Same with purchase documents, you can see the deleted ones when filtering them out. Purchase - All Purchase documents - Deleted documents shown, when clicking on Show it will again show any deleted purchase documents where you can see the document number and date, but not be able to open it.