Hi Marty1403, 

Thanks for posting here in the Community.

As mentioned by @john-pero, QuickBooks Online (QBO) only saves information that you've saved. I'll pass this along to our product developers' team to let them know of your business needs.

In the meantime, you can manually recreate your invoice.

For future reference, please check this article in case you want to restore a deleted transaction: Use the audit log to re-enter deleted transactions.

Let me know if you need further assistance, We're always right here to help.