Q: Error message in Itunes

Yes, restore the software to be able to use your phone.

Try this procedure:

Turn your device off and connect your cable to the computer, but not the device just yet. Start up iTunes. Now, hold down the home button on your device and plug it in to the cable - don't let go of the button until iTunes tells you it's detected a device in recovery mode. Now you can restore to factory settings.

Have you tried it on another computer?

Error 3194, Error 17, or "This device isn't eligible for the requested build" - Apple Support

Have you jailbroken or otherwise hacked your phone? Has it been dropped or damaged in any way? It sounds like you may need to take it in to an Apple Store Genius Bar to be evaluated for a possible hardware problem.