Your inventory items may not be gone, but you have Filters turned on that are returning no results.
From the Inventory module, make sure you are viewing the correct Group (A) and check your Filters (B).
To quickly turn off your active filters, click on Clear all or you can click on each filter to select different filtering options.
Next Up: Learn how to customize the columns displayed in the Inventory
And how about the opposite....you delete all your items and still quartzy is showing as you have them, but when exporting to excel, the sheet appears empty? what to do to get the product number to zero?
I think you also send a ticket to Support about this issue. I may have figured out a resolution to this so if you can reply to that email with the information I requested, that would be great! Thanks!