Cannot total inventory across multiple worksheets.

Hello, I am a excel newbie trying to learn the system. I am creating a master inventory worksheet for medical supplies. The goal of this worksheet will be inventorying what we have, and what we need in order to order a resupply. The Workbook will be multiple worksheets within the same workbook, and each sheet will represent a single storage container that will have a bunch of different items. At the end of the workbook, I want to create a master sheet that contains the totals from the previous pages, in essence, the item (including its identifier code or skew), the total in stock, and the amount that we should have in stock. There are two problems that I keep running into. First, the same item may be found in different boxes, for example bandages may be both in worksheet 1 and worksheet 4, and they need to be totaled together at the end. Secondly, the order of items in the box can change depending if I have them ordered by name or by identifier code. I want to be able to sort through my list without it messing up the inventory at the end.
Any help would be appreciated, keep in mind I'm pretty new to this so I get lost about as easy as a 5 year old.

Here is a started workbook. I have the total number of pages that I need, including a page for large items,
and a last page for total inventory. There are 5-6
pages with some items filled in.

This is pretty much perfect, I am going to spend sometime trying to learn from your macro. The only problem I am bumping into is it isn't totaling all the sheets, there were a few items in the last box (#19) that did not make it on the totals sheet at the end, and I'm not sure why. Thanks so much!

This is pretty much perfect, I am going to spend sometime trying to learn from your macro. The only problem I am bumping into is it isn't totaling all the sheets, There were a few items in the last box (#19) that did not make it on the totals sheet at the end, and I'm not sure why. Thanks so much!

This is separate from the original task which works perfectly.
The goal would be to plug in the NSN number in a box, any box, and have the rest of the info fill in. So if I punch in NSN "1564-566-25-5643"
under the first column, it will automatically fill in the component number and the item name. I would imagine that information that automatically fills in would have
to be on a new separate master-sheet, because I don't have all the items or their component numbers available to me yet, so it would have to be something I can add to overtime.
This would be especially helpful if it was a separate "master" workbook, because I will make multiple copies of the original inventory spreadsheet you created.
Each of our Medical Kits has 20 boxes, however, I have at least 5 medic kits that I will be inventorying and accounting for, and although they carry many of the same items they aren't identical.

Copy that. I will try to work through this one on my own for a bit, just so I can learn, and hopefully help others out someday. You sir are a wizard, and I greatly appreciate the help.