what do you mean when you say "enter something on your computer"?
if you lower the volume physically do you hear any sound? if you do it may be physical problem.
have you tried to reinstall the sound driver. go into device manager, right click on "sound, video and game controllers" and look for audio controller, right click on it and uninstall, then restart your computer and let the computer reinstall the driver again.
while you are in device mananger look if there's any ? or ! in yellow inthe sound, video and gave controller section. your problem may be related with that ? and ! item. post back with your findings.
another thing you may want to try after you have attempted the previous solution is to look for an updated driver at the
manufacturer website.
good luck!