Go to your course in Moodle and click the [Turn editing on] icon in the upper left corner of the screen.
Click the Add an activity or resource option under the week or course section that the file belongs. This will open a new window.
On the “Add an activity or resource” pop-up window (and under the “Resources” section), select the File option and then click [Add].
On the “Adding a new File” page, type a name for the resource or document in the Name field and add a description if you choose. The file’s name will appear directly on your course page.
In the Content section click the [Add...] button.
On the “File picker” pop-up window that appears, select [Moodle Server Files (my courses)].
Use the folder directory to navigate to where your file exists (for example, in a previously-offered course).
Select the file you want. (You will have to navigate to the file’s “Files” folder, then its “Files and subfolders” folder, then the file itself.)
Click the [Select this file] button.
Back in the “Adding a New File” page, scroll down to the bottom of the page and click [Save and Return to Course].