How do I downgrade 4.2.1 ios?

[ProfessorJordan]

I wanna jailbreak my phone again,i have an iphone 4 16gb,im sick of not being able to customize it,is there any way i can down grade it back so i can jailbreak it,i go to jailbreakme.com but says ios to new,please help,what if i do restore will that go back to my old firmwire?

 

[iGaz]

An untethered version will be here soon. If you can't wait you need your SHSH's (blobs) for 4.1.

Did you press the make my life easier button in cydia or use tiny umbrella to save them...?

 

[ProfessorJordan]

whats untetheried version,and shsh's, why do i just downgrade it
i found a link of here

 

[iGaz]

You need SHSH's to downgrade. Apple doesn't like you downgrading so you have to get round it with SHSH's. Since you don't know what they are you probably won't have them.

You can jailbreak with redsnow easily but it will be tethered. Everything is explained here...