Negative Inventory on Balance Sheet - QuickBooks Desktop

How to Find if your data file has Negative Inventory?
Run the Inventory Valuation Detail (IVD) report in QB:

In QB, select Reports>Inventory>Inventory Valuation Detail.
Click the Dates drop-down and select All.
Find all occurrences of negative amounts in the On Hand column.

How to Fix Negative Inventory?
Adjust the transaction dates such that bills are dated before invoices:

From the QB menu, select Reports and then Inventory and then Inventory Valuation Detail.
Click the Dates drop-down arrow and select All.
Scroll through the report to an item that is showing a negative amount in the On Hand column.
If you can do so legitimately, adjust the dates of the bills and/or invoices so that the bill dates are before the invoice dates.
Repeat the steps for each item with a negative quantity in the On Hand column.
Caution: It is not sufficient to adjust the current QOH to a positive value. You must eliminate each occurrence of negative QOH.

Another option, consider buying a 3rd party file repair service. They will analyze your file to identify the items and dates the quantity on hand (QOH) went negative and then fix all occurrences of negative inventory. The repaired file will not have negative inventory and will verify correctly in QB. There may be a change to the COGS and Inventory Asset account balances after the repair. There will also be a change to the Opening Balance Equity account that will be used to add the inventory adjustments. You will need to add adjusting journal entries after the repair.