The vibration function doesn't work anymore, why?

If you haven't, make sure you've got all the correct settings! (Settings> Sounds)

Have you tried any basic troubleshooting yet??

First try a hard reboot- press and hold the Sleep/Wake button along with the Home button for ~10 seconds until the Apple logo appears.

Before you take it to Apple, try to restore the iPhone. First, sync the iPhone to update the backup on your computer and then choose "Restore" from the "Summary" tab. If you don't try this step, the Mac Genius you speak with will have you do it at the Apple Store anyway.

If you're still having trouble, the iPhone will be replaced, not serviced/repaired, at the Apple Store.

Hey SoCalSkippy,

So when you toggle the ringer/silent switch(shows a red dot when silent) on the left side of the iPhone it does not vibrate?

Try resetting or restoring the iPhone.
http://docs.info.apple.com/article.html?artnum=305743
http://docs.info.apple.com/article.html?artnum=305744

If it still does not vibrate after a restore it may need hardware repair. You can contact AppleCare or Make a reservation to speak with a Mac Genius.
http://www.apple.com/retail/
U.S. iPhone technical support: 1-800-MY-IPHONE (1-800-694-7466)
http://www.apple.com/support/contact/

Jason

as has been posted many times, sometimes the vibrate mechanism getting stuck is the reason. if the previously posted attempts to reset, etc do not work, try this - with the phone turned off, give it a firm "tap" on the side with your hand. turn it back on and toggle the vibrate mode on and off. hope this helps!

You said it won't restore now. Is it giving you an error message?

Note that in most cases if you're under warranty and it's an obvious physical defect they'll probably swap out your phone for a refurbished model on the spot.

By "without your iPhone" they mean they would likely try a restore first, so they'd probably have you leave your phone there rather than have you sit at the Genius bar for an hour or two.

In most locations that's a great excuse to go see a movie or get some other shopping done. 🙂