If you have no knowledge of how to go about such things, you would need to be prepared to learn it from reading the many articles to found on the Internet. Also, if you want to try and fix computer problems, you need to be prepared for the fact that they can be made worse instead of better. One thing can lead to another sometimes.
A good place to start would be to read the Windows Help and Support files. They have a 'Fixing a problem' section there. One of them is about sound troubles. Follow the steps next time you have no sound. Anything that you find wrong, have a search for the symptom on the Internet. See if it has been encountered by anyone before and read what the cure was.
If this approach doesn't help and you are not particularly interested in going further (or don't have any 'know-how' in this field), perhaps it would be best to take note of the last sentence in my post above.
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