I accidentally upgraded to 6.1.3. Did a tethered jailbreak through redsn0w. But it was useless, cydia wasn't working. Every time I opened it, got crashed!
Then I switched back to 5.1.1 (thanks SHSH blobs)
The reason for switching back again to
5.1.1 is that it is consuming a lot of battery + the feel and look of iOS 6 was awesome!