This is the article to use, if your shuffle is the current 4th gen shuffle
If there is a problem with syncing after enabling VoiceOver, you may want to do a Restore. On the shuffle's Summary tab, click the Restore button. This will erase the shuffle, reinstall its software, and set it to default settings.
When the shuffle restarts, it should go through the process described in the linked article above, where it says To enable VoiceOver when you set up iPod shuffle. Follow those steps to see if you can get VoiceOver enable.