If you mean that they are not active, then you can start them with the “start” button on each shield tab in the main GUI, or using the tray icon.

If you mean that you can’t see them even listed in the main GUI of Avast, then you can run the installer in “custom” installation and select the shields you want.

In case this doesn’t work,

1_ download the clean uninstall tool;
2_ download the latest stable version of the edition of Avast that you need/want;
3_ reboot into Windows Safe mode and run the clean uninstaller for all your versions of Avast that were installed in the past;
4_ reboot into Windows Normal mode and use the latest stable installer.
Using the custom installation you can double check that all the shields are being installed.
5_ finally reboot and check if the shields are there as you want.