Restore jailbroken iphone? Can't remember iphone passcode?

Ok so heres what happened

i went braindead for a second and couldnt remember my iphones passcode and i kept trying to unlock it and now its one the "iphone disabled connect to itunes"… I have no problem restoring it but the thing is that the iphone is jailbroken and i heard if you connect a iphone to itunes that is jailbroken it locks up or something. This isn't my iphone, its my brothers, so if i something happens and i accidently mess it up he will most likly be mad… So my question is, can i restore it thru itunes if its jailbroken with installous and cydia, if so how, and if not what do i do? Thanks and when you answer, remember your talking to a total noob when it comes to all this iphone, firmware, jailbreaking stuff…

Plug it into iTunes, Restore and update as long as it says 5.1.1, then once restored it will be ready to jailbreak with Greenp0ison or similar.

in short, Jailbreaks are TOTALLY wipeable by simply restoring through itunes with no risk