How can I use an existing data disk with re-installation on RPi?

Hi all sensei,
I could only find one other question on the same topic, but no satisfactory solution in it, so asking again. I did move my data disk to an external usb drive earlier and recently my HA crashed and refused to boot anymore. So I decided to re-install it, for RPi 3B.
When I rebooted with the new HA micro-SD, it initiated as usual without detecting my external data disk. So the data disk is just plugged in to the RPi, but HA is working with it’s internal one. Can anyone guide on how can I tell HA to start using the existing external data disk, and everything on it that I already configured earlier?