Installed Win10 Installation Media. How to find existing data?

Hi
I installed "Win10 Installation Media" on a flash drive (to help rescue data on another laptop) but didn't realise I had important files already on the drive.
The "Win10 Installation Media" install created a new drive on the flash drive and I can't see my old data. I'm sure it is still there but I don't know how to access it as only the new drive name shows up.
Hope that makes sense...any help/ideas would be appreciated.
Thanks

It may be possible to recover some data, even if the drive had its partition deleted and formatted.

An example of recovery software: https://www.tenforums.com/general-support/

Anything that was overwritten by the Windows installer is gone. That could be anything that was on the drive. When the data were deleted, the storage addresses were made available, so the new data wouldn't have been written only to what was previously blank space.

An example of file recovery software: Download Recuva | Recover deleted files, free! (I have never used it.)

Best of luck. I hope that the "important files" aren't too important.

Thank you. Will give that a shot.