No Sound From Headphones; Mouse Problems - Dell XPS M2010 Owner's Manual

Ensure that the subwoofer and the speakers are turned on —
See the setup diagram supplied with the speakers. If your speakers have volume controls, adjust the volume, bass, or treble to eliminate distortion.
Adjust the Windows volume control —
Click or double-click the speaker icon in the lower-right corner of your screen. Ensure that the volume is turned up and that the sound is not muted.
Disconnect headphones from the headphone connector —
Sound from the speakers is automatically disabled when headphones are connected to the computer's front-panel headphone connector.
Test the electrical outlet —
Ensure that the electrical outlet is working by testing it with another device, such as a lamp.
Eliminate possible interference —
Turn off nearby fans, fluorescent lights, or halogen lamps to check for interference.
Reinstall the audio driver —
See Reinstalling Drivers and Utilities.
Run the Dell Diagnostics —
See Dell Diagnostics.
NOTE: The volume control in some MP3 players overrides the Windows volume setting. If you have been listening to MP3 songs, ensure that you did not
turn the player volume down or off.

No sound from headphones

Check the headphone cable connection —
Ensure that the headphone cable is securely inserted into the headphone connector.
Adjust the Windows volume control —
Click or double-click the speaker icon in the lower-right corner of your screen. Ensure that the volume is turned up and that the sound is not muted.
Mouse Problems
Check the mouse cable if using a USB mouse —
Shut down the computer. Disconnect the mouse cable, check it for damage, and firmly reconnect the cable.
If you are using a mouse extension cable, disconnect it and connect the mouse directly to the computer.
To verify that the problem is with the mouse, check the touch pad —
1. Shut down the computer.
2. Disconnect the mouse if using a USB mouse.
3. Turn on the computer.
4. At the Windows desktop, use the touch pad to move the cursor around, select an icon, and open it.