For some reason, Word is not displaying the field codes in your document.
Hold down the ALT key and press the function key F9. If for any reason the ALT and F9 combination does not work, please retest the problem, after changing your Word setting by the following way.
For MS Office 2021, 2019, 2016, 2013, and 2010 please try the following steps
1. Select Options from the File menu.
2. Click on "Advanced" and scroll down in the 'Advanced options for working with Word'.
3. Uncheck the box for "Show field codes instead of their values" present under "Show document content" as in the following image.
4. Click the OK button
For MS Word 2007:
1. Open MS Word 2007 and click on the Office Button.
2. Click on Word Options, when the new windows open, click on Advanced.
3. Scroll down through the ‘Advanced Options’, until you come to the group Show document content.
4. Uncheck the box beside Show field codes instead of their values. Click on the OK button.
For MS Word 2003:
1. Open MS Word 2003 and select the option from the Tools menu.
2. Go to the View tab (it will normally display by default) and search for the “Field codes” check box in the Show group.
3. Now uncheck the checkbox for “Field codes” and click the OK button.