i it happpens if you reboot a computer an then don`t use the audio straight away
na, that's incorrect! It just sounds like something has been removed from the computer such as software assocated with the device or hardware driver itself and it no longer works. Having the speakers plugged in etc will make no difference, as long as the sound card is physically connected to the motherboard, then that's all that matters.
Your resolution is to find out what sound card you have in your machine. if its built onto the mother board, do a search on the board's model number on the manufacturers website to get the relevant software. if its a plug in card, do the same, get the model number from the card and do a search for the drivers.
Windows update probably won't find the device driver, if the device is unrecognised by Windows.