I've an old music CD and it's all scratched, is there anyway that i could check if there is any unreadable part on it?
fsck for CDs/DVDs?
There are some tools you can use to recover data on the CD (well, not all data, anyway).
The tools I think of are
ddrescue - copy data from one file or block device to another gddrescue - the GNU data recovery tool
dares - rescue files from damaged CDs and DVDs (ncurses-interface) dares-qt - rescue files from damaged CDs and DVDs (Qt-interface)
Take a look at Rubyripper. Do a rip of the CD in question. When that's complete you'll get a .log file which will report on how the rip went.
it will repair any files so that it's impossible to successfully blind-test with the original via an ABX test for example. The log file will optionally report any position that needed more than 3 trials, so you can check the position yourself.
That's the best I can think of.