ITunes purchased when restored from back-up wants me to authorise each one

Question

Original pc 'died' - hard disk error but I managed to back-up my ITunes libraries to an external drive. I have copied the contents to my new laptop but they are not appearing on my ITunes library (similar to HUGGYUK previous problem). When I attempt to play the music which I had already paid Apple for on my old pc, it keeps asking me to 'authorise' each item. I then attempt to sign in and it does not recognise my sign-in although I can use this sign-in to access the ITunes store. So I now have 'bought and paid for' 1100 records approx which I cannot use.
Help,please

Answer 1

Taking the first issue. If you copied the iTunes folder from your old PC onto the external disk, and you had all your tracks in the iTunes Media folder in the iTunes folder, then it should be very simple.
In order to check if things will work - that is to say this is a test not the answer.
Plug in your external drive. Then hold down the shift key and start iTunes. Keep holding the shift key until you are prompted to choose a library. Navigate to the iTunes folder on the external drive and choose iTunes Library.itl.
If you do this, do you get your old library back as it was on the old PC?
You can switch back to your internal drive again by repeating the shift key start and choosing iTunes Library.itl in the iTunes folder on the internal drive.
On the authorisation issue, did you try the things I suggest adn if so what was the result?
Tracks bough from the iTunes store some time ago were DRM protected so the PC needs to be authorised to play them. The tracks will be Protected AAC files if you look on the general tab in Get Info and the files will have the extension .m4p.
More recent purchases are not DRM protected and will show as Purchased AAC audio file.