Are you getting 16xx, 1015 errors? Is the restore failing? Read below and hopefully this will assist you. Firstly I just want to set the picture, Im no iPhone expert, I had to read about 20 different articles to fully understand what to do, if this doesnt work for you please dont ask me questions as I wont know the answer. Before you continue please make sure you meet the following requirements. 1. You have a iPhone 3GS 2. You are / were running 4.2.1 3. You have the saved SHSH files (for version 4.2.1) on either your local system or Cydias servers. If you are using your local system I presume you have knowledge of tiny umbrella 4. A Windows 7/XP system with USB functionality 5. A Apple Sync cable ***IF YOU DONT HAVE THE SHSH FILES YOU CAN NOT RESTORE YOUR iPHONE (Apple only sign the latest version) Follow these steps (Presuming you have the SHSH files on your local computer) Run Tiny Umbrella 1. Download Tiny Umbrella (hXXp://thefirmwareumbrella.blogspot.com/) 2. Install Tiny Umbrella and move your SHSH files into the required directory (Save SHSH Directory under the advanced tab) 3. Start the TSS Server Make sure you are not running Skype Make iTunes think your Apple.com (so you can self-sign the restore during the verify) 1. Right click on your desktop, click New>Shortcut 2. In the type location of the item prompt just type notepad and press return 3. Now right click on this new icon on your desktop and click Run as administrator 4. Now open the following file c:\windows\system32\driverrs\etc\hosts 5. Now add the following line to the bottom ; 127.0.0.1 gs.apple.com If you have any other references to gs.apple.com enter a hash (#) before the line EG 127.0.01 gs.apple.com #75.X.X.X gs.apple.com Save the file and exit, lets test that worked . Click Start>Run and type CMD, press return. You will get a black command box. Now type ping gs.apple.com you should get a reply from 127.0.0.1 (by the way this is your local loopback) If you dont and get something else clear your DNS cache and try the above again, heres how to clear the DNS cache From the black command box again type the following ipconfig /flushdns Try the ping again, if must have a reply from 127.0.0.1 if this fails again you must have got the hosts file incorrect. Ok so we now have Tiny Umbrella working and we and pretending to be apple and we have the SHSH file to sign the restore.. we are getting there. Generate a custom IPSW You cant use a stock IPSW file as you have upgraded your BB (06.15.00) I failed here about 10 times until I worked that out. It really does pay to read forums!!!! 1. Download the 4.2 PWNAGE (Sn0wbreeze) tool from here.. (hxxp://ih8sn0w.com) 2. You will now need the original 4.2.1 IPSW for the iphone 3GS found here (http://appldnld.apple.com/iPhone4/061-9895.20101122.Cdew2/iPhone2,1_4.2.1_8C148a_Restore.ipsw) Run Snowbreeze and follow the onscreen guide, once this finishes you will have a Custom IPSW file that doesnt include the BB update. Ok so we now have Tiny Umbrella working and we and pretending to be apple and we have the SHSH file to sign the restore and we have the custom IPSW we are getting very close now. Get your phone into the right state. Download iREB from here, again (hxxp://ih8sn0w.com) Now run iREB (You need to make sure you are using WIN XP SP 2 compatibility mode or it will throw an error) do this by right clicking on the iReb program>Properties>Compatibility Select Run this program in compatibility mode for choose Windows XP (Service pack 2) Follow the onscreen instructions You device should now be in a PWNd DFU mode Ok so we now have Tiny Umbrella working and we and pretending to be apple and we have the SHSH file to sign the restore and we have the custom IPSW and the phone is in PWN DFU mode we are getting incredibly close now. Update in TUNES Now open iTunes (make sure tiny Umbrella is still running) hold SHIFT and click on restore, browse to the custom IPSW file we created earlier. The phone will take about 10mins to restore itself. DO NOT SWITCH THE PHONE OFF GIVE IT TIME. BANG! You should now have a restored iPhone, please comment below if this worked for you!