I-phone wont start

Iphone Connect With Itune
Turn Off Your Phone
Press Home Button ( 5 Second )
After 5 Second Press Power Button (9 Second )
Release Power Button
Still Holding The Home Button
Itune Detect Your Iphone In D.f.u Mode
Release Home Button

Your Iphone In D.f.u Mode With Blank Screen
done
then,you can jailbreak and unlock your iphone after restoring it w/ itunes
heres the guide for jailbreaking and unlocking iphone.....

http://www.iclarified.com/entries/index.php?caid=2&scid=11&seid=2
http://www.iclarified.com/entries/index.php?caid=2&scid=11&seid=1

Dont worry... in most cases its not a problem... just press both buttons (home and power) at same time for 10 to 12 secs and voula there it goes the apple logo appears again!
cheers!