I have version 4.2.1 and modem firmware 6.15.00. I don't know what to do. Plz help me
1-Get tinyUmbrella and save that iOS shsh.
2- Backup your files using iTunes.
3- Get the latest redsnow from the dev-team blog site.
4- Download ipsw 4.2.1 from Internet and save it on your desktop for a faster accessibility.
5- update your iTunes.
6- connect your phone to your computer and run tinyUmbrella, click the icon "start TSS server" and follow on screen instructions till iOS 4.2.1 restoration is done completely.
7- in case you've disconnect your phone after the iOS restoration, connect it back to your computer and open up redsnow. Clic "browse" and locate the ipsw file on your desktop, once ipsw successfully identified tap "next" button, once patching finished a new page will come up automatically with some option, leave everything UNCHECKED except "install cydia". In fact it's already that way by default so don't change anything on that page unless you know what you are doing, then next follow up the redsnow onscreen instructions to put the phone in DFU mode and let redsnow do the job.
8- once jailbreak is done, close up everything and open up iTunes having your phone connected to the computer, then restore your backuped files to your iPhone,
Now you can power off and on without the need of a computer.
Good luck.
