What Happened to my "pages"?

More information is needed. What do you mean by "can't access"? Do you mean you can't find them? Or you can't open them; if that's what you mean, is Pages still installed? Or do you mean that you can't view them with Quick Look? Or what, exactly?

It's difficult to offer much in the way of advice with so little to go on.

Regards.

Are you getting any error messages? What are they? Does the program try to open the documents?

~Lyssa

By 'system tray' do you mean the Dock, or do you have some sort of third-party launcher?

Does Pages open on its own?
Have you tried opening Pages and then opening the documents from within Pages?
If your select a Pages document in the Finder and Get Info (cmd+i), what application is listed in the Open With section?

My goodness, what a fix you're in.

Did you install any updates before this happened? You say you had just upgraded to Leopard--mind giving details about how you updated?

Let's see here. Try repairing permissions using Disk Utility. You can do this by opening Disk Utility from the Applications>Utilities folder, or by restarting your computer with the Install Disc 1 DVD inserted and holding down the C key to load the Installer. Once the Installer has loaded, click the Utilities menu and choose Disk Utility.

Once you have Disk Utility running, choose "Repair Permissions." If anything can't be repaired, try one more time. If it fails again, post the message here.

Try using Pages under another user account. If you don't have 2 already, create a new one in System Preferences under the "Accounts" option.

Best of luck!

~Lyssa

"The application Pages quit unexpectedly. Mac OS and other applications are not affected." Then I have the option to relaunch (doesn't work), report (I did) or relaunch (didn't work).

Well that's some useful information not previously available.
Open up your username/Library/Preferences folder and move com.apple.pages.plist to your desktop.
Now try to open Pages again.

Pages is no longer listed in my applications.

Ok, gotta ask again as your terminology is not very clear. Do you mean the main Applications folder or your own user Applications folder, or something completely different? The main folder is where it should be, and it is located in your hard disk/Applications.
Now, previously you said that you get an error message that it quit unexpectedly, which differs from this post saying you don't have Pages.

Since you upgraded to Leopard, it may be possible that you no longer have Pages on your hard drive, depending on how you upgraded. If you chose "Upgrade" or "Archive and Install," then you should still have all your documents and Applications. If you chose Erase and install, then you won't have pages and will have to re-install it from your original copy. If it came installed on your computer, they it will be on the original install disks.