Anyone know anything about jailbreaking iphone?

i just attempted to do it. my old iphone (1st gen) was WAY better when it was jailbroke! i tried with my new 3G (2.2.1) and it said “success!” complete! and the phone never booted up. it got stuck at the apple logo. i tried restarting and everything. nothing worked. so i put it in recovery mode in itunes and restored it to a new phone, and am now restoring it to my yesterday backup. which should be fine. but will i lose all my contacts if i didnt have any contacts on my pc. i dont store contacts on my pc. but i dont choose to sync them to it either. they were JUST on the phone. when i restore will they be back??? i NEED those!!!