Learn how to Reset your Permalinks in WorPress, in this walk-through video. This will often correct a 404 error, or issues after a server move. Below is an outline of the steps:
1. Login to the WordPress Dashboard.
2. Click Settings.
3. Click Permalinks.
4. Choose a different permalinks setting than what you have, then click the Save Changes button.
5. Select your original setting, then click the Save Settings button again.