Unjailbreak

1-Go to Cydia

2-Serach for Cydia Installer

3-Unninstall it

4-Go to:http://www.redmondpie.com/download-5.1.1-ios-for-iphone-4s-4-3gs-ipad-ipod-touch-direct-official-links/ Go down and select your device

5-Download it

6-Connect your Device To iTunes

7-Go to the device menu on iTunes  and press restore and shift at the same time

8-browse the file that you have downloaded

9-Let it Restore

10-Thats it

Note: If you have problems please tell me. I will help