MS Word Table of Content fix

I have a 141 page MS Word document (all text) containing 8 Table of Content (TOC) headings and approximately 175 subheadings. The original document was created in MS Word with a fully functioning Table of Contents. This file was then converted to a PDF in which the Table of Contents worked perfectly. \r\n\r\nWe now need to make changes to the document (including adding and deleting headings & sub-headings) but unfortunately we have lost the original Word document and are now working from a new word file that was converted from PDF to Word.\r\n\r\nThis conversion (from PDF to Word) has unfortunately disabled all of the Table of Content functions, including:\r\n- Automatic linking from the TOC to the linked document section.\r\n- Automatic updates (including new numbering sequence) to the TOC when new heading/subheadings are added to the body of the document.\r\n\r\nWe would like you to fix the TOC in the entire document so that it functions properly, including with the two functions described above.