Q: Hello , I have Iphone 4s , while updateing to ios 7.1,suddenly it gave me the itunes sign and error 4013 , i need help , how to fix that

Hello AymanGendy,

Thank you for the details of the issue you are experiencing with your iPhone.  I found an article that specifically addresses error 4013.

Follow these steps:

Resolution

Try these steps to resolve the issue:

1. Install the latest version of iTunes.
2. Restart your computer.
3. Make sure your computer is up to date. If an update requires a restart, check for updates again after you restart.
   
   • Learn more about updating OS X.
   • Learn more about updating Windows.
4. Restore using another USB cable.
5. Restore your device on another computer.

If you continue to see error 4005, 4013, or 4014 when you restore your device,contact Apple for support.

Learn more about other update and restore errors.

Find the full article here:

iOS: Restore errors 4005, 4013, and 4014

http://support.apple.com/kb/TS5314

Thank you for using Apple Support Communities.

Best,

Sheila M.