Try the following
cd /mnt/cdrom/"file directory" then
cp "file" "new location"
What happens is you change to the directory where the file is located & then you can use cp to copy it to the new location (full path name needed here).
Another way I do it from a backup looks like this:
cp /mnt/cdrom/home/foo/filename /home/foo
I find I have it a little more control over it when I use the full pathname for the file I want to copy.
edit: nuts always seems to happen I start to post & someone has already beat me to it