Sorry you're missing the old Messenger sounds. The good news is that you can get them back! Here's how:

1. Click this link.
2. A dialog opens, asking you if you want to Open or Save this file. Click Save.
3. Another dialog opens asking you where you'd like to save it. To make it easy, just save the file to your desktop.
4. Double-click the .zip file on your desktop to "un-zip" it. A window opens listing all the classic Messenger sounds! Leave that window open.
5. Find My Computer—it's either on your desktop or in your Start menu in the lower left of your screen. Double-click it.
6. Navigate to C:\Program Files\Yahoo!\Messenger\Media.
7. Double-click Local Disk (C:).
8. Double-click Program Files.
9. Double-click Yahoo!.
10. Double-click Messenger.
11. Double-click Media.
12. OK, enough double-clicking! Leave the "Media" window open, and move it beside your open .zip window.
13. In the .zip window, select all the sound files: click the first one, then hold down the shift key and click the last one in the list. Click, hold down and drag this list into the Media window.
14. A Confirm File Replace window opens, asking you if you want to replace the existing files. You do, so click Yes to All.

All right! Done. You can close these windows now and move the .zip file to your Recycle Bin. The old sounds are back!