As the above post is completely unuseful (as are most of their recent posts I've noticed) my advice would be to try and see if you can get iTunes to recognise it by putting it in DFU mode.
I'm not sure as to why it's decided to break all of a sudden - it could be down to a number of reasons but it's happened so we'll concentrate on fixing it.
What firmware were you on before? Do you rely on an unlock to use your phone?
Try and aim to restore your phone back to the firmware you were on. Don't just click restore in iTunes as this will put you on 3.1.3 and although you're able to jailbreak, an unlock is yet to be released.
Once you've got iTunes to recognise it, depending on the firmware you wish to go to, do a custom restore to that firmware and the re-jailbreak. You shouldn't have to do anything special just because you've been jailbroken before.
Let us know how you get on.
IDK how you can say pixelated's posts are not useful?? You need the info he requested to GIVE advice.
You again state in this thread that 3.1.3 can not be unlocked, however, you don't know what iPhone version the OP has. If he has a 2G, he can certainly unlock. Also, unlocking is dependent on the baseband, not the OS. Finally, if the OP has a 3G and it is capable of downgrading the baseband via Fuzzyband (i.e., the oldest 3G's with bootloader 5.08) he can unlock.
There's just a lot you need to know when an OP leaves out info, before you can give advice.