Q: iTunes music from last 2 months has disappeared!

About 2 months ago and added approx 6 albums into iTunes from ripped CDs, I then sync'd them onto my iPod and also uploaded them onto the Google Play cloud (as I have a Nexus 7).

Although I use my Mac daily, I hadn't used iTunes since adding these albums until last night when I planned to add a few more CDs.  But amazingly everything I'd added in the last 2 months was gone! 

I can't understand how they got deleted but everything had gone.  I've since recovered the tracks (via Time Machine and Google Play) but does anyone know if there's been any know bugs in iTunes.  I seem to recall there was an update to iTunes fairly recently - could this be the cause?  Maybe iTunes thought the files were corrupt and deleted them?

I've never seen anything like this before (I've been using iTunes for about 8 years) and I've never had any other problems with files disappearing.

Thanks,

M.