Something is unclear for me here … but let’s do it the old fashion way. Download the Oracle_VM_VirtualBox_Extension_Pack-6.1.14.vbox-extpack
Or from their site:
https://www.virtualbox.org/wiki/Downloads
From File Manager open Terminal in that place/folder where you save it then run this command:
sudo vboxmanage extpack install --replace Oracle_VM_VirtualBox_Extension_Pack-6.1.14.vbox-extpack
To make sure all is ok, also run this command:
Reboot the system and all should be back to normal.