no driver in windows 8

hi i am samartha i am a user of windows 8.1 pro which i have just installed and i have encountered a problem which is my hp rock 2.0 speakers model no.HP 5187-8366 rev b is not working when i slide my mouse over the audio icon in the windows taskbar its in this image it says "No audio output device is installed" and when i go t device manager and press update driver it says this device driver is up to date. i have no hardware problems for my speakers in my pc. So, what do i do? Please help me.