Word 2010 Multilevel list - Numbers disappear

I just read through all the suggestions and what I ended up doing because nothing else worked, was to copy and paste the document into a new word document. When I copied the document, I made sure I did not copy the last paragraph mark in the document.  This seemed to work and make me wonder if somehow the document is getting corrupted.

Sure wish Microsoft would fix this problem and save all of us the time and headaches!!

Since copying to a new document worked, corruption may have been the underlying problem.

However, it is difficult to tell without knowing more about the document. For example, did you set up numbering according to the instructions in Shauna Kelly's article at http://shaunakelly.com/word/numbering/numbering20072010.html? Did you avoid using Quick Style sets?

If possible, you can upload an example of the problem document (remove any sensitive information first) to OneDrive or Dropbox and post a link here.

This is a annoying bug in Office 2010. Use the Organizer to copy the Heading styles from a previous version of the document. To find the Organizer, include it into the ribbon (File -> Options -> Customize Ribbon ->(All commands) -> Organizer. Clcik on the Organizer in the ribbon. In the right pad, Close the Normal.dot and Open File to browse for a former version of your document, selecting "all Files" in the lower right corner.  Copy the headings that do not number correctly, it is often sufficient just to select the higher level heading.

Actually, if you are having problems with numbering, copying individual styles may not be the solution (for the reason that copying numbered styles has been unreliable in several versions). Instead, create a new document from a good (corruption-free) template and then import the existing text via the Insert File dialog box (on the Insert tab, click the arrow on the Object button, and then click Text from File).

Actually, this is a poor advice, since after having done all this work, you will be faced with the same problem again. The bug in Word 2010 is that when two headings of different Levels follow, e.g. 3.4 followed by 3.4.1, when deleting the 3.4 Header, all Heading3 of the document lose numbering.

One cannot reapply the Heading3 style because it is the root style "Heading3" that has been modified, although the Option "Automatically Update Styles" is disabled on all headings. It is tedious to renumber the headings correctly, this was fine until Office 95, but since then every Office Version made it more difficult to configure. The root of the Office 2010 bug seems to lie in a paradigm shift in the way the paragraph styles are inherited when the end of paragraph sign (inverse P) is deleted: formely, the text of the paragraph whose end of paragraph sign was deleted received the style of the following paragraph, which was logical. In Office 2010, the following paragraph receives the style of the deleted end-of-paragraph sign, which is illogical. Actually, the method that I propose works correctly while the one you propose asks the user to do an unnecessary work. And no, I did not find that copying styles with the Organizer had any bug until now.