I own an Acer Aspire M and have had the same problem for months. I finally figured it out! Here is what to do:
-Make sure that the sound on the video/music screen is enabled. (on and turned up)
-Look at the bottom right of the toolbar on the homescreen of your computer. (where the start button normally is) There is a icon that resembles a speaker. Make sure that this is not muted! For some reason, mine came from the factory set on mute. *If you have a Windows 8 system, go to the "desktop" screen. (You know, the original screen that came before Windows 8)
-Turn the volume completely up. You will be able to control the volume of your earphones through the video/music screen.
To conclude, there are two volume control panels, the one on your video/music screen and the one that is on the bottom right of your toolbar. Make sure that they are both un-muted and turned up. It finally made my earphones work again! I hope that this helps someone.