updgrading ios, unknown error oocured (3004)

Hi, pulati.

Thank you for visiting Apple Support Communities.

Here are the steps on how to resolve update error 3004.

Errors 3000-3999 (3004, 3013, 3018, 3164, 3194, and so on): Error codes in the 3000 range generally mean that iTunes can't contact the update server (gs.apple.com) on ports 80 or 443.

1. Update to the latest version of iTunes.
2. Verify the computer's date and time are accurate.
3. Check that your security or firewall software isn't interfering with ports 80 or 443 or with the server gs.apple.com.
4. Follow these steps to troubleshoot security software. Often, uninstalling third-party security software will resolve these errors.
5. An entry in your hosts file may be redirecting requests to gs.apple.com (go to "Unable to contact the iOS software update server gs.apple.com" above).
6. Internet proxy settings can cause this issue. If you're using a proxy, try again without using a proxy.
7. Test restoring while connected to a known-good network.

iTunes: Specific update-and-restore error messages and advanced troubleshooting

http://support.apple.com/kb/TS3694

This could be related to the host file being modified. Go to the section labeled Blocked by configuration: (Mac OS X/Windows) > Windows or Mac > The hosts file may also be blocking the iTunes Store.

iTunes: Advanced iTunes Store troubleshooting

http://support.apple.com/kb/TS3297

Cheers,

Jason H.