All my purchased music is gone after updating to IOS5?!

I contact to you on my mother's behalf, since she's not an experienced computer user.

Few months ago She bought, the latest iPod Touch, because she thought it was the easiest and smartest way to store music rather than that she should invest much more money in music systems and stacks of CDs. Since you are able to buy music from iTunes on your iPod.

Yesterday we signed on to her computer, because I knew there had come a new operating system for iPod and other apple devices (IOS5). After we had installed the update on her iPod, it turns out suddenly that all her music on iPod is suddenly gone, so all the music she has purchased through the iTunes Store on her ipod touch is gone.

I must admit that it seems very disturbing that there is any visible opportunity to get her purchased music from the iTunes Store back again.

I can not quite understand why the music has not been synchronized with her computer for all the app's lying on her ipod was imported to iTunes on her computer. But not the purchased music. I would think that you had a kind of library where you could download your purchased music from, but not.

and she has not the "Purchased" button on her device when I she goes into itunes, which I find highly problematic.

I must admit I was very unsure whether I should buy an iPhone 4s now, if all your music disappearing when there are updates and something goes wrong.

Hope we can find a reasonable solution to the problem here, because I do not think it shoud be right that we should buy the same music again.

And sorry for my bad english i hope you understand me, i'm from Denmark.