Thanks for posting your question here. We would need to look into some specific examples of where your inventory has not been tracked properly to figure out why that happened so I'm not sure what may have gone wrong at this point.
However, if you are just looking to be able to revise your listings in bulk at this point, I believe all you will have to do is disable the Inventory setting in your account, which can be done by mousing over the "My Account" tab within your account, selecting the "Inventory" option under "Settings, unchecking the box next to "Use Inventory Management" and then clicking the "Update Inventory Preferences" button at the bottom of the page.
I hope this helps. If you need any further assistance with your account, or if you are looking to find out more about why your inventory was not tracked properly in the past, please contact our customer support team by mousing over the "Help" tab within your account and clicking the "File Support Case" option.