Here is an example for a jscript that you can use to update your library:
var ITTrackKindFile = 1;
var iTunesApp = WScript.CreateObject("iTunes.Application");
var deletedTracks = 0;
var mainLibrary = iTunesApp.LibraryPlaylist;
var tracks = mainLibrary.Tracks;
var alltracks = tracks.Count;
var numTracks = alltracks;
var i;
while (numTracks != 1)
{
var currTrack = tracks.Item(numTracks);
WScript.Echo(numTracks + " of " + alltracks);
// is this a file track?
if (currTrack.Kind == ITTrackKindFile)
{
// yes, does it have an empty location?
if (currTrack.Location == "")
{
// yes, delete it
currTrack.Delete();
deletedTracks++;
WScript.Echo("Geloescht " + deletedTracks);
}
else
{
currTrack.UpdateInfoFromFile();
WScript.Echo("Updated " + numTracks);
}
}
numTracks--;
}
if (deletedTracks > 0)
{
if (deletedTracks == 1)
{
WScript.Echo("Removed 1 dead track.");
}
else
{
WScript.Echo("Removed " + deletedTracks + " dead tracks.");
}
}
else
{
WScript.Echo("No dead tracks were found.");
}
Copy the contents into editor,
Save it to a plain text file with the suffix .js
Right-click on the file and execute it in the command shell (otherwise you will be prompted for every file).
The script will run through your iTunes library and delete references to non-existing files as well as update the data for existing ones, if necessary. It will not add files to the library.
Updating a library of 70000 entries will take hours.