How can I restore the original ringtones and sounds? Without really thinking, I used the "clear data" command on the Media Storage app, which deleted all the stock ringtones and notification sounds from my Nexus One. How can I get them back?
If you are rooted, you can push this collection of media files to /system/media/  

Without root, android should still locate the files if you place them in a folder on your SD card called "media" and retain the rest of the file structure from the zip.