How do I return my system to a prior configuration?

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http://askubuntu.com – My flash player recently started playing videos 4 times as fast with no audio. I've tried removing then reinstalling my flash, but it hasn't worked. My teacher recommended I try returning my system to a configuration before flash player became flawed. I've looked elsewhere but I haven't been able to find an explanation of the process if it exists. (HowTos)