Not quite sure what you mean. Are you trying to restore the phone and jailbreak? Or are you trying to restore the phone using Cydia (like the SHSHs or something??)...
Yes I have saved SHSH's with cydia I have never had to restore with cydia till now. I have a 3g with 4.1 I would like to go back if you could help it would be great thanks
Steps:
1) Open Sn0wbreeze
2) Create your custom firmware with the stock 4.1 ipsw, use expert mode if you'd like to activate the phone without an official carrier's SIM
3) after custom fw is built, open iTunes
4) shift+restore to your custom 4.1 firmware
5) you should have a jb 4.1 iPhone 3G after the restore finishes.
Last edited by i.Annie; 10-07-2010 at 12:43 PM.
Reason: Automerged Doublepost
Yes I didn't mention unlock as an option because you said you're on 4.1 unjailbroken so you must've upgraded, rendering your baseband upgraded to a not unlockable state.