Error 21

[firestorm]

I have a iphone 4 (4.0.1)that was jailbroken and running fine for 18 months.As my contract ran out i changed the sim from 3mobile to gifgaff.I had to change the setting for the carrier which i did and the phone was running fine.Then i found out that with giffgaf you could not share your internet connection with so to get round this i used MyWi app from cydia.This worked and the phone was running fine.Until yesterday i did a reboot of the phone and it would not reboot only the apple logo would show on the screen.
So far i have tried
1:Restore it with itunes to which it gose through the motions then comes up with error 21
2: tinyunbrella(which i have used before and have saved my SHSH) which comes up with can not start Tss server pid 2.9 mut be killed.

If i hold the menu button and the power button then let go of the power button i can get it to connect to itunes but then get the error 21 again
I would just normally take it to the shop but i need my phone 24/7 as i am a carer and my phone has a lot of important numbers in.
Any help would be great
ps if it help i am using a mac laptop
thanks

[cablefreejunkie]

search forum for error 21,,i had this ages ago and im sure fijiman posted a fix for this

[smirnoff_rules]

[ame=http://www.youtube.com/watch?v=BgxO9i5eGag&feature=related]Error 21 FIXED WORKING!! - YouTube[/ame]

or

You need to keep two buttons pressed at the same time: Home key and Power key
You will get a notification that informs you to slide the bar to turn off. Just ignore it.
If you see that the iPhone***8217;s screen become back, then it means you are in DFU mode.
At this time, your iTunes software would be disconnected from your iPhone device.
Hold down on the home key and let go of the power key. You also need to press down the home key until your device is gets connected by the iTunes software.
And finally***8230; when your Apple iPhone is in DFU mode, your screen would get black by doing this, and you can get rid of the iPhone error 21.

[dik]

Check your hosts file, tiny umbrella by default modifies it and blocks apples server which is needed when doing a restore, there will be a line with apple in it this needs to be deleted and your pc rebooted or you will get errors from iTunes

[firestorm]

after 2 days i managed to sort it,I had to download a new ipsw run it through redsn0w,extras,select ipsw
Then i had to goto /ect/ and open the hoist file copy it to desk top(in order to alter it as the file is locked in /ect/) i deleted the last line and then moved it back to /ect/
Then i had to connect the phone and with redsn0w use the pwned DFU option.
Then select the ipsw file i down loaded click on it and itunes will start hold the alt button while itunes starts
Then leave it to instal and bing my phone was working again.

[dik]

It was the hosts file ~~~~ed up by tiny umberella, either dont use that again or find the check box in tiny umberella that says ~~~~/don't ~~~~ with the host file on exit and tick/untick it, hosts can be edited where it is, you just need admin rights