Can't hear audio from headphones (realtek high definition audio)

Hello,

i just finished installing my windows 8, and then rebooted.
When rebooted, i found out the microphone did not work, so i installed the realtek driver from here:
http://www.realtek.com.tw/downloads/downloadsView.aspx?Langid=1&PNid=24&PFid=24&Level=4&Conn=3&DownTypeID=3&GetDown=false
Then i rebooted.
I installed steam and other programs and played some portal 2 (with headphones)
Everything worked fine until the next reboot.
Now the headphones don't work anymore.

Does any1 know why?

my specs:
Computer: Asus K53SV
OS: Windows 8