500GB USB drive changed into 31.9GB "boot" disk

[BasMS]

Dell laptop with Windows 8.1
I commanded to create a boot disk on my 500GB USB drive which contains ~300GB of files.
Then noticed that it was stupid, so I stopped it.

Now the 500GB USB drive with roughly a thousand files (my pictures, etc) shows in Windows explorer as a 31.9GB empty disk.
After the boot formatting it contained a few start-up / boot windows files which I deleted. And some other files (pictures), which I transferred to the C-drive.
But I cannot reach the ~1000 other files that are outside the 31.9GB...

What to do save my files?
I have 700GB free on my C-drive (=1GB).

Thanks already for your effort!

 

[laviniuc]

try recuva, https://www.piriform.com/recuva/download might help you get your files back

 

[BasMS]

try recuva, https://www.piriform.com/recuva/download might help you get your files back

Thank you!
With Recuva I could save ~10 files that were in the 31.9GB disk.

However I could not find a method to save the ~thousand files.
Assume that those are in the 512GB - 32GB = ~480GB area that is outside the new formatted boot disk of 32GB.

How to read that ~480GB?

 

[laviniuc]

under advanced there should have an option to search in data not partitioned (as in, the missing partition) and there's a checkbox for deep searching. can take a while but should help you find the files if the data isn't overwritten.