Missing lots of media since update

[Feek]

This evening I updated my iMac to 10.10.4 and also did the latest iTunes update.

My daughter just asked me where everything's gone because there's a load of stuff missing from the AppleTV.

Upon checking, I have just 11 films and no TV shows since 2013.

This is all stuff I've ripped myself as I use iTunes as my media library. I should have nearly 850 films and around 1900 TV episodes.

All the files are there.

I've tried holding down the option key and reselecting my library but it's still the same.

Anyone else had this missing media issue since the updates today?

 

[Feek]

I've restored the following files from my Time Machine backup

These are in the iTunes folder. When I start iTunes, I can see all my media but then the filenames change slightly and all the media vanishes. It's as though iTunes is rebuilding the library but in a broken way.