In order for you to regain access to the quick access pins that may have been lost, follow the steps below in order. If you can't resolve the issue after attempting all the steps. Submit a helpdesk ticket or if you already have one, follow up with the results.
1. Open your File Explorer.
2. Double-click on the address bar at the top. Photo of address bar below
3. Copy and paste the following, %AppData%\Microsoft\windows\recent\automaticdestinations .
4. You will be taken to a file path will multiple files, click on the "Select All" option. Photo of option below.
5. After selecting all the files, proceed with deleting all the files, by either hitting the delete button or right clicking on the files and choosing the delete option.
6. You will need to repeat steps 1-2 .
7. Copy and paste the following, %AppData%\Microsoft\windows\recent\customdestinations .
8. Repeat steps 4-5.
Now upon opening your file explorer, the options that were missing should reappear. Note: You may have to re-pin any of the custom pinned locations.