hi,
If theres no headphone jack, where are you plugging it in? if you're plugging it into maybe a line out port, or something, you might want to open up volume control by right clicking the speaker in the taskbar and going to open volume control. Check that what you've plugged it into isn't muted or the volume is on low. If it isn't listed there, try going to Options, Properties, and tick it to show up.