Hello Julien01,
Thank you for providing the details of the issue you are experiencing with iTunes. Your iTunes media and the iTunes application are stored in different locations, so even if you are experiencing an issue with the iTunes application, your music will be safe. I recommend the following article for the issue you are experiencing with iTunes not launching:
iTunes for Windows XP: Troubleshooting unexpected quits, freezes, or launch issues
http://support.apple.com/kb/TS1421
Once iTunes is running again, check to see if your purchased albums have downloaded. If you are not able to locate them, I recommend the following steps:
If your download was interrupted using your Mac or PC
- Open iTunes.
- Choose Store > Check for Available Downloads.
- Type your account name and password if prompted.
iTunes: How to resume interrupted iTunes Store downloads
http://support.apple.com/kb/ht1725
If they still do not download, try downloading them from your list of past purchases:
iTunes 11 for Windows: Download previous purchases from the iTunes Store
http://support.apple.com/kb/PH12491
If you are still not able to download the albums, I recommend reporting this issue to the iTunes Store:
How to report an issue with your iTunes Store, App Store, Mac App Store, or iBooks Store purchase
http://support.apple.com/kb/HT1933
Thank you for using Apple Support Communities.
Best,
Sheila M.