Usually, when you plug headphones into the headphone jack, the Realtek icon will pop up a balloon saying "INFORMATION: You just plugged a device into the audio jack".
Suddenly, these balloons have ceased. The Realtek control panel shows the headphone jack as "occupied" all the time, regardless of whether or not anything is plugged into it. The laptop speakers will not work at all (except to play the Asus sound right at bootup, so I know the speakers themselves are still functional.)
There is indeed the partial software solution for this annoying hardware problem. It has to be made through registry. In regedit.exe search the dword parameter ForceDisableJD (It occurs twice in all registry). Change it both times from 00 to something else (01, FF doesn't really matter) and reboot the system. You will at last be able to hear your laptop's internal speakers. But this crutch has two confusing problems. First, when you plug headphone jack in, the sound from internal speakers doesn't fade at all, sound goes both from headphones and internal speakers. Second problem - internal microphone doesn't work at all, you have to plug external microphone in order to speak (e.g. in Skype). But if you really have to use laptop's internal speakers from time to time, this can be a tolerable solution, nothing prevents you from setting ForceDisableJD parameter back to 00, when you don't need internal speakers to sound.
Yes, I had some headphones plugged in and then unplug them and notice the sound not come back. It happened twice in my laptop. The first time I managed to solve the problem by twisting jack in semi-plugged positing. When It happened the second time, nothing was helpful, even complete disassemble of jack hole made by specialist. The reason was obvious - the jack which caused this problem was too thick and curved. One hope still remains is to change this broken jack hole with a normal one, taken from some other broken laptop. For now I use mentioned registry key when need the sound from internal speakers. It's simply the cheap and temporary solution of such problem, not the best one. There is no warranty for my laptop because it was ordered in US and brought into my country (laptops are cheaper in US than in Eastern Europe).