Had the same problem. Try this:
1. First, open Windows Update to see what updates you’re receiving. You can easily find it by entering Windows Update in the Start menu search.
2. Look underneath the Windows Update box to see what you’re getting updates for. By default, Windows 7 will only check for updates to Windows and drivers, not other Microsoft products such as Office. To add this, click the Find out more link on the bottom.
3. This will open the Windows Update page in your default browser. Check the I agree box, and then click Install.
4. Accept the UAC prompt, and then after a moment the page will update and show that Microsoft Update is now installed.
5. Check for updates. If MUI doesn't show you might want to wait a day to check again.
OR you might want to check if you're using other than Ultimate or Enterprise edition since those 2 are the only versions that have MUI.
Hope it helps