If you glue the two halves together, you will still not be able to read
this normally. If you can see ANY light through the cracked area after
the glue job, (and you will) that will be decoded as missing data and
you will get a Cyclic Redundancy Error. There may be some special
recovery software in existence that can "average" the gaps out and still
recover the music files, but I am sure it will be very expensive. I had
a customer who had her business data on a CD that was scratched and
unreadable. I sent her to a data recovery specialty shop, and they were
able to remove the scratched plastic a millimeter at a time until the
laser was able to focus on the data and recover all of it. But the cost
was over $2000.00 to do the job.