Lomega external hard drive formatted and unusable

Registration date
Monday July 3, 2017
Last seen
July 3, 2017
- Updated on Jul 3, 2017 at 02:16 PM
Hi guys!
I am a stupid idiot. That's a good start to a question I guess.
I put the Microsoft media creation tool on my 300gb Iomega external hard drive (some ears old, I guess it is the LPHD-UP 300GB), instead of onto a blank USB flash drive.

I wanted to find out, how much space it takes and what size of USB flash drive to use in the next step, because Microsoft didnt tell anywhere.
So i started the process. At the very end (99%) i said: "we will now format. Do you want to proceed." I said no. Of course.
I thought in my next step I open the explorer to see the amount these files take. I open the external hard drive and I am shocked: instead of a capacity of 300GB it had 32GB and everything was "deleted", at least my own folder structure was gone and my files invisible and unaccessable.

Can you guys tell me
a) how to get back to 300GB? I thought I can do that will an OEM driver. I cant find a driver for this device in the net.
b) how to recover/restore my files?Yesterday, I gave asoftech's recovery tool a try and it found a bunch of data on it. But I dont want to spend 39,95$ to then find out that the data is unuseable. Can u recommend a good software for around 20$? Asoftech's interface sucks.

Thank you very much in advance!

Lenovo notebook, 2015
Windows 8.1, 64bit