Hi Yes I had exactly the same thing as you. I lost all my sound and the taskbar changed colour. After lots of head scratching and tearing out of hair I tried uninstalling Yadis backup program that I had recently installed and hey presto my sound came back. If you havent installed Yadis then its all a coincidence.
Got to admit I am getting very wary of installing new stuff. Only last week I installed
IOBit SmartDefrag. Couldnt shut the pc down after. Ended up uninstalling it and all was ok. Does anything work properly and not b...r up you pc?