Library sync issue

In an effort to move my I Tunes library to a new computer I used
a large storage device. I then dragged the file onto the I Tunes desktop short
cut. All of my files are in the newly downloaded utility. The only songs that
will sync to my I Pod classic are those in the cloud. I'm getting a dialog box
when attempting to sync that says there are songs that could not be copied
because they could not be found. Additionally there are songs I bought tonight
that do not sync. I restored my settings in the I Pod and attempted again but
got the same result. Any idea how to resolve this issue?