Internal Speakers dont work but headphone jack does

I have a studio xps 16 running vista 64-bit service pack 2. the other day i was on skype and skype mutes all other audio on the computer when on. i ended up uninstalling skype and my built in webcam because i read that together they sometimes screw up audio. so the next day i tried to listen to music, no luck. I ran a diagnostics and when it got to the colored bars and asked if i heard a beep I HEARD THE BEEP so that means the problem is a system problem and not a screwed up sound card. (i think) anyway i updated all of the drivers, the device manager has no ? marks. i talked to dell and the found a virus that MAY have been eating away at my registry. i got rid of that and still no audio. i didnt really wanna touch the regedit because im nervous cuz u can really f up a computer if your not sure what your doing. i also did a system reboot to about a week before it happened with no luck. by the way, under the device manager it says> Sound, video and game cotrollers and then my options are> ATI Function Driver for High Definition Audio - ATI AA01 and> IDT High Definition Audio CODEC

So any ideas guys? i dont wanna re-download the os and start over so what now??

i just ran a command prompt system scan as an administrator and got the following message:
Microsoft Windows [Version 6.0.6001]
Copyright (c) 2006 Microsoft Corporation. All rights reserved.
C:\Users\Brendon>SFC /scannow
Beginning system scan. This process will take some time.
Beginning verification phase of system scan.
Verification 100% complete.
Windows Resource Protection found corrupt files but was unable to fix some of th
em.
Details are included in the CBS.Log windir\Logs\CBS\CBS.log. For example
C:\Windows\Logs\CBS\CBS.log
C:\Users\Brendon>


i dont know that anyone knows what that means though...