Hello LizMarthouse!
Thanks for reaching out to us. Let me assist you with the item receipt.
Ideally, it'll unlink from the purchase order when you delete a bill created from the item receipt. Then, you'll be able to create a new item receipt for the same purchase order.
What I can suggest is to open the purchase order. Then, simply click the Create Item Receipts button to create a new one.
Also, you'll want to run the Verify and Rebuild Data tool in QuickBooks Desktop. This is to ensure that the company isn't damaged which could be the reason why the pop-up to link purchase order to item receipt isn't showing.
In addition, update your QuickBooks Desktop to make sure that all the latest patches and fixes are installed.
I added some articles if you need a detailed guide on how to track transactions in QuickBooks Desktop.
I'll keep an eye to this thread if you need more help. Thanks!