If you insert a text box in a Word document, but the text box is not visible and does not appear, then the color of your text box border is definitely set to none. The text box was not inserted successfully.
If you want the text box to be displayed, use the following method.
Like the following figure, select the text box object, when you choose, you can probably guess where to insert the text box, use the mouse to click, if selected, there will be eight white dot control point, and then, right click, pop-up the following picture of the menu.
In the illustration above, select Format text box to pop up the following Figure dialog box.
In the diagram above, switch to the color and Line tab, where you choose the Color "black" above. You can see it only if you have a color on the border of the text box.
Finally click on the "OK" button to confirm and exit, you can see the displayed text box.