As it says in the title, I linked my PSN to this Battlenet address and my online characters, including shared stash have vanished. I’ve tried a multiple restarts and reinstalls to no avail.
What do?
Look at the blizzard thread. This means you already had your psn account linked to a battle net account, and when you linked it to a second one your chatacters are gone, because well on the new one you didn’t have any characters.
So unlink, then link to your old one, the one you had before and they will come back.
EDIT
Link: