That is, I don't know why your TOC is behaving that way, except that I found that in your language translation preferences, Arabic was set. I changed to English and French, but that did not seem to have any effect. However, by copying the entire document, minus the final paragraph mark (there are two empty paragraphs at the end, shown when you display hidden characters (Home tab, paragraph symbol, or press Ctrl+Shift+8), and pasted into a new Word doc. the TOC function works fine.

Hope this helps.

Ulodesk

Thanks Ulodesk for your reply.

1. What do mean by language translation preferences? Is it document property or paragraph property?
   Please notice that I have made English as the default in all language settings in Word's options.
2. When you copy & paste the entire document minus last paragraph mark, which paste option you have selected (Match destination, keep text only, ...)? Because I did the same but I have selected Keep Source Formatting from paste options as I want to preserve my styles. Unfortunately, the issue still exist in the new document.
3. I think it may be something related to Regional settings of my system. I will review these setting & see what could happen.