What does "to disc" mean? What are you calling a "disc"? Hard drive?
Floppy disk? CD? DVD?

Exactly how did you do the copy and from where did you copy these
documents? Please tell us the exact verbatim text of the message you
get when you try to access the files on the "disc." It's hard to be
sure based on the little information you're supplied, but my guess is
that you may have copied shortcuts to the files, not the files
themselves, then deleted the original files.

If that guess is correct, your only recourse is recovering the deleted
documents from the original hard drive. First try the recycle bin. If
that doesn't work, read on.

"Deleting" a file doesn't actually delete it; it just marks the space
as available to be used. There are third-party programs that can
sometimes recover deleted files. The problem is that the space used by
the file is likely to become overwritten very quickly, and this makes
the file unrecoverable.

So your chances of successfully recovering this file are decent if you
try recovering it immediately after deleting it, and rapidly go
downhill from there. If you've been using the computer since then (for
example to write this question and read this answer), your chances may
be very poor by now.

But if the file is important enough, it's worth a try anyway. Stop
using the computer in question immediately, if you haven't done so
already. Download an undelete program (here's one:
http://www3.telus.net/mikebike/RESTORATION.html but there are several
others to choose from; do a Google search) on a friend's computer and
bring it to yours on a floppy to try.

If this fails, your only other recourse is to take the drive to a
professional file recovery company. This kind of service is very
expensive and may or may not work in your case.