I added hyperlinks and a table of contents in Word, but the PDF I made has links that do nothing when I click them. How do I fix it?

You probably created the PDF with Print to PDF. That printer treats the page as paper and drops links and bookmarks.

Use the export option instead: in Word choose File > Save As or Export, select PDF as the type, and click Options. Make sure Create bookmarks using Headings is ticked and that ISO 19005-1 compliant (PDF/A) is not ticked, since that mode can limit features. Then save.

Test the result in a normal PDF viewer and not only in a browser preview, because some previews do not follow all link types. If a link is still dead, check that it starts with https:// in the Word document.

Save As PDF fixed the links and table of contents. Thanks.