Need some help!

I have an Iphone 4 on 4.1 that I jailbroke with limera1n on the day of the release, everything has been fine until now. I went into cydia to purchase My3g and as soon as it was dowloading my phone went to the power up screen and has been that way every sense. Any suggestions? I am at work so I dont have access to my Itunes. Thanks

just try holding down the home button and the power button on top, for 10-15 seconds, most likely you will see the Apple logo.

The Apple screen is where I am stuck, I can only turn it off and on.

Oh i see, then if what i said up there doesnt work you can do nothing till you get to itunes.