Yes. It was jailbroken with redsnow
Ah, c'mon man, we need more info that that......virtually anything you can think of that lead this is what you should say.
What iOS are you on?
Which redsn0w did you use?
I bet you jailbroke tethered on 5.1, went to reboot, your phone is in a loop now?
Is that right?
If so, this is because 5.1 has a "tethered" jailbreak.
You have to plug in phone, open redsn0w, click "Extras".
Then enter DFU mode.
Once in DFU then click the "Just boot" button.
Of that is not the problem......then please......give us details.
I mean, that's like a person posting a whole thread saying "hey....my phone is broke. How do I fix it?".
I mean how are we suppose to help if you tell us almost nothing, except for what the phone is doing. Common sense really.