Help! Jailbroken iPhone got updated and now I cannot jailbrake phone!

[marcosegarcia]

How do I downgrade the software on my iPhone to a jailbrakeable software without having to have my phone jailbroken first?

 

[marcosegarcia]

Or is there a way to jailbreak 4.2.1?

 

[Jmills87]

You can only downgrade your iPhone if you have the SHSH blobs saved for the firmware you want to downgrade to. 4.2.1 can be jailbroken via Greenpois0n.