Help me with sound please anyone. I hate computers?

When I test my sound on my computer i here the chime, but when i try to listen to music or listen to youtube i hear nothing. When i click on the Open Volume Mixer all the slides are on 100; yet things still dont want to work on anything else. My speakers wont sound nor my headphones. Only when i test it I hear. This is very fustrating. What do I do?