apple mobile device support. How can I download?

Hi, Jose.

The best option would be to uninstall iTunes and all of it's components, then download and install iTunes again.

Removing and reinstalling iTunes, QuickTime, and other software components for Windows Vista or Windows 7

http://support.apple.com/kb/ht1923

However, if you want to reinstall the Apple Mobile Device Support driver, see the section labeled Verify that the Apple Mobile Device USB Driver is installed > For Windows Vista, Windows 7, and Windows 8 > Reinstall the Apple Mobile Device Driver.

iOS: Device not recognized in iTunes for Windows

http://support.apple.com/kb/TS1538

Cheers,

Jason H.