Hello, kyawmyintshein85.
Thank you for visiting Apple Support Communities.
Here are the steps that I would recommend going through when experiencing restore error 3004.
Resolve communication issues
Check the hosts file or TCP/IP filtering, which might cause communication issues between iTunes, ports, and servers.
Common errors: 1004, 1013, 1638, 3014, 3194, or 3000-3999. These alerts refer to gs.apple.com, say "There was a problem downloading the software", or say the "device isn't eligible for the requested build".
Resolve specific iTunes update and restore errors
http://support.apple.com/kb/TS3694
Also, make sure to process and updates for iTunes and your computer.
Cheers,
Jason H.