Always keep at least one backup of important data.

And backup means a secondary copy stored somewhere else not like some people that calls the external drive/usb stick the particular backup but they don’t have the data anywhere else.

That drive is toast, never ever plug it in again and if you want the data let a real expert try to recover what is still left. Be prepared that it is expensive (€1000+ usually around €2500) but it is usually free or cheap to check if there is anything for the drive/possible to recover.

Hope you can save some of that data.