1) Update your iPhone to 5.1.1
2) Download Absinthe
3) Plug in iPhone
4) Right Click your iPhone name and hit "Backup"
5) Now hit the RESTORE button (then confirm you want to restore to factory settings)
6) Wait for restore to finish remembering not to touch anything, dont setup the phone or anything. Leave it alone.
7) Once you see the grey iphone screen with the slide to unlock run Absinthe.
8) Once it has done it says ENJOY
9)Now go into iTunes Right Click your iPhone and hit RESTORE FROM BACKUP.
10) Depending on how much data you have it will all be done once it has restored.