how to change posts time and date

[josef1]

i had a problem with threads/posts time , my server time had a fault and went forward +12 hours

so when i correct the server time most of new thread posted are not coming in order
as last threads after correcting time are not coming in order and where old thread/posts with wrong time still on the front of the thread/forumdisplay

any way to correct the time of thread/post by a hack or otherway.

Thanks