Copying folder from W7 to W10 appears unreadable and using 0 bytes

I have a laptop with corrupted installation.

A corrupted installation means that the files on that drive are also corrupted. You may be able to read the files on the corrupted drive but moving them results in corrupted data. Try running Check Disk with the /R switch (ie) chkdsk /R from an Elevated Command Prompt on the corrupted drive first, before attempting to backup. This will check for bad sectors and try to move the data to a good sector near by. It will take a while.

Try viewing your inaccessible folder when you boot from a boot disk (or command prompt outside Windows (i.e. without Windows running). This would verify that it's writing the folder that's the problem, rather than reading it.

E.g. boot to a command prompt - if familiar with that- e.g. using shift + left click Restart, or booting from a Win 10 install medium via Repair your computer, or use Kyhi's boot disk available from the top of the Software and Apps section (boots to its version of Win 10). The latter would also allow you to try the hash check I mentioned above- assuming you can actually open the folder and there's something there.

Conversely, you can try writing the folder to your disk when booted as above, then boot into Windows and see if you can read it.

Thanks for replying but, corrupted installation in this case means "a windows with booting problems".

What caused the booting problems? Possibly Bad Sectors on the HDD where the install is. It will not hurt to run Check Disk on the drive, and it may solve the problem.

Then, i reconnect the HD to the laptop and install Windows 10 64bits Anniversary Edition (build 10586).

It seems he reinstalled Win 10 on the HDD where it was failing.

Could be worth checking the disk anyway just in case:
Hard Disk Sentinel (trial).