Hello Stjovite,
According to your symptoms in my experience I would be fairly certain your modem is just bad. If you haven't made any changes to your operating system since 2 weeks ago or any hardware changes, then it is pretty safe to say your modem is bad. Especially if the self diagnostic says the modem is not responding.
The only thing to try is to reseat the modem (unplug and replug it back in) and/or change the modem to a different PCI slot.
Hope that helps!
