External hard drive defective / unrecognized?

After my laptop is now running again with a new internal hard drive, and I reinstalled Windows over my old external hard drive, we somehow misinformed it or did not recognize it properly. I called them "my data" before, but after installing Windows, they still have the install date, and the external hard drive is now called "ESD-USB," as I have never called them. Furthermore, I see in the "Properties" that the hard drive has only a storage space of 30 GB, where it could previously save up to 1 TB. May someone help me? I do not understand all that.

Look under "Create and format hard disk partitions" (just type in the Windows search bar) and look there to see if something wrong, not assigned or otherwise missing and if the disk is completely recognized.

How did you install Windows from the old disk?
With the Microsoft Media Creation Tool only DVDs and USB sticks can be created.

In case of doubt, that would delete the old record and thus its "installation medium".
I think he should therefore wait with this possibility.
I'm puzzled by the "installation of the old record".
That sounds pretty exotic.

An unassigned drive letter is not a problem, you can always assign it, even if data is on the disk!

If you have used the Media Creation tool to reinstall with the external hard drive, then you have formatted the external hard drive and deleted the data there.

If you're lucky, you can recover some files with a data recovery program.

I'm afraid the MediaCreationTool it does not matter if you formatted a USB stick or a whole USB hard drive to the installation medium…

Could be - I have not tried it yet. 😉
It would be only the first approach to understand what the questioner has done exactly. The description allows for various interpretations.