I have an iPhone which was on a jailbroken 1.1.4 FW. I was using this messenger thing on my phone and it just froze. I pressed the home button but nothing happened. I then pressed the home button and the power button together and it shutdown the iphone. I turned it on again and that apple logo came but nothing happeded. I left it for 1 hour and still it was the apple booting logo. I called my iphone from another phone and call goes but the iphone doesn;t ring.

I then decided to restore as my last option. As I have iTunes 7.7 it restored and updated my phone to 2.0. As I have an iPhone from the states it says my o2 sim is an invalid one. I put in my AT&T sim and asked me to activate. I haven't activated it. I just wanna know how can I use my phone again. Its frustrating..........Can someone help !!!!!!!!!!

P.S. I use a PC and not MAC if that info is of any relevance .

Search for pwnage 2.0.1, read, download and follow instructions to jailbreak, activate and unlock.
It's a piece of cake.
Of course only on a mac though... I just reread your post.
Search for downgrade to 1.1.4 from 2.0.
The process is a pain in the ass, but if you want your phone back, then you will have to follow it.

I have tried to downgrade itto 1.1.4 via the tutorial on iClarified but it just doesnlt do it. comes back with an error as soon as i try to restore to 1.1.4.
Please help !!!!!!!

can anyone help???