Item Average Cost and Item Quantity

Hello

We have an item that has zero quantity on hand, it shows a current value of $0.01 but has an average cost of $22,517,998,136,850.58 ????.

We also have several items that show ridiculous on hand quantity in list view but when you click into the item there is no quantity on hand.

I have attached a preview of these errors.

How do these figures arrive and how do we correct them.

Thank you

Cathie