Deauthorising a dead device

I need to deauthorise (remove) a couple of devices which no longer exist - I'm using 2 authorised devices (tower PC and iPhone) but need to add a third (laptop). I've actually got 5 devices authorised, with with no access to the old ones as they are defunct. If I deauthorise all 5 in order to reauthorise my existing devices and add my new laptop, will I lose my extensive iTunes library? I've invested an awful lot of money in buying downloads from the iTunes store, and I also keep a lot of special tracks in iTunes which I've created myself - recordings of my choir singing, practice tracks for them created in Sibelius, my own compositions. I can't afford to lose my iTunes library. Thanks in advance.