ITunes 8 - my entire library has disappeared!

Question

I admit I am not very tech savvy, but I have successfully upgraded my iTunes in the past. However, when I downloaded iTunes 8, all of my music and podcasts and everything disappeared. My iTunes is empty. I found my iTunes Folder in my owner folder, but now I am stumped. Help!

Answer 1

Is your Library missing, or your physical music files missing, or both? This is an important distinction which you did not explain.
This Article is useful: No music shows up in iTunes after upgrading
As may be the concepts in this one: All of my music is missing after downgrading from iTunes
Perchance you may still have the music files on your PC -- but not seen in iTunes or the PC.
Do a thorough search of your PC for your Music Files using the tips below:
First - Make sure that you enable your Windows Explorer to view 'Hidden' files:
1) Open Windows Explorer
2) Select 'My Computer'
3) On the main Windows Explorer menu: Tools=>Folder Options=>'View' tab
4) In 'Advanced Setting' --> Files and Folders --> Hidden files and folders:
4a) Select 'Show hidden files and folders’
5) Click 'Apply to All Folders'
6) Click 'OK'
Then check using Windows Explorer in 'My Music\iTunes\iTunes Music\...' for folders containing your music (or wherever you keep your music folders).
Also check in your Recycle Bin to see if you accidentally deleted it. If so, ‘Restore’ it back to it’s original spot.
Then try running a search using Windows Explorer (or similar) for files with the extensions of: m4a, m4p, MP3, OR with the partial names of the songs you are missing.
Do all the above before you decide that your music files have been completely erased from your hard drive.
IF you can locate the music files/folders, we can get iTunes to recognize it. Try one of these:
If you have a backup iTunes database file available....
1a. Close iTunes.
1b. If you have a backup (or previous version) of the ‘iTunes Library.itl’ database file, then place a copy of that file in the ‘...\My Music\iTunes’ folder (or wherever the current, incomplete file resides). Also look in the ‘Previous iTunes Libraries’ Folder for the backup ITL files saved by iTunes prior to an upgrade. You can use this file as well.
1c. Open iTunes
If you have a full version of the iTunes Music Library.xml file available....
2a. --- Within iTunes: File=>Library=>Import Playlist and browse to the location of the XML file
2b. --- Select the XML file and allow iTunes to Import the music information
If no backup ITL or XML files exists….
3a. --- In iTunes choose: Edit=>Preferences=>Advanced tab. Select 'Change' and browse to the music folder in your PC drive (if it isn’t already). Click OK to save that setting.
Then....
3b. --- In iTunes choose: File=>’Add Folder to Library’ & browse to the music folder in your PC drive. Click OK.
Without the ITL file or the XML file, re-‘Adding’ the music files to the Library will lose you the Ratings, Play Counts, Date Added and Last Played attributes, as well as your Playlists. No real way to recover them if you haven’t made prior backups. Something to consider for the future.
IF your music files are truly gone, and you have some or all of your music files on your iPod, these links will give you several methods of recovering whatever songs remain on your iPod; some free, some third-party software, some more comprehensive for restoring Playlists, Ratings, Play Counts, etc. Read them and their associated links before deciding on a strategy that works for you. There are many various third-party software programs that will offer a more robust process, or an easier GUI. Do a Google search for them if the links below leave you wanting.
Don King Resurrected: Deleted files from hard drive (free user steps – music recovery only)
MacMuse: Computer Crashed (free user steps – music recovery only)
Copying music from iPod to computer (a primer on various methods and software)
Copying Songs from Your iPod to a Mac or PC (resource for 3rd party software)
iPodRip Software (Free trial: Mac & Windows)
PodUtil Software (Mac & Windows)
YamiPod Software (Free: Mac & Windows)
PodPlus Software (Windows)
TuneJack Software (Windows)
Senuti (Mac OS X v10.3 or higher Recovery Utility)
XPlay (Windows software For Music Recovery &/or Cross-Platform Functionality)
XPlay Photo Browser (For recovering Photos)
Extremely Simple & Free Method: (just to recover the song files – may not work on a Mac)
1 - Open iTunes
2 - Edit=>Preferences=>’Advanced/General’ tab
2a --- Select ‘Copy files to iTunes Music folder when adding to library’: checked
2b --- Select ‘Keep iTunes Music folder organized’: checked
2c --- Click OK to store changes
3 - Attach your iPod to the PC and hold down the ‘Shift+Ctrl’ keys until the iPod is fully recognized (this will defeat the auto-sync process)
4 - If you get a dialog box to link the Library, decline this option
5 - Within iTunes: Edit=>Preferences=>’iPod’ tab: switch iPod to ‘Manually manage songs & playlists’ – click ‘OK’
6 – Eject iPod
7 – Close iTunes, then reopen iTunes and attach the iPod (it’s in manual sync now)
8 – File=>Add Folder
9 - Browse to and open ‘My Computer’ (click on the ‘+’) and select the iPod (or the lower ‘\iPod_Control’ sub-folder)
10 - Click OK
The music files should start to transfer back into iTunes with its correct information
This will take some time depending on your PC’s speed and the amount of songs on the iPod
No Playlists, or Ratings, Last Played, & Play Count attributes will be transferred from the iPod to iTunes using this method.
If you have problems with seeing the iPod within 'My Computer', try again switching your update method to 'manual', detach the iPod, then reconnect the iPod to the PC.
AFTER recovering your Library, strongly consider developing a thorough backup strategy for just this type of situation.
You need at least two full sets of your music, not including what is on the iPod:
a) One full set on the PC within iTunes (on internal HD or ExHD)
b) One full set on an separate external backup medium (CD/DVD/ExHD/other)
c) One (full or partial) set on the iPod
Music files on just the iPod and only one other medium is not considered having any backup.
If you cannot store your complete music files on the computer’s internal HD, then create and maintain at least two external sets (any multiple combinations of ExHDs, DVDs, CDs).
Backup both the music files and the Library database file (iTunes Library.itl). What are the iTunes Library files?
Here is a post on developing a thorough backup strategy:
http://discussions.apple.com/message.jspa?messageID=9095648#9095648
Best of Luck