When i first installed ubuntu 12.04 everything worked fine. All of a sudden my sound has stopped working!!

This has happened before [like 2 days ago], however the next day it started working again. That may happen again...[I've already rebooted 5 times]

My Sound Card is a HDA intel PCH

My Sound Chip is Intel CougarPoint HDMI

My machine is an Acer TimelineX 3830TG, heres my lcpci output

00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09)
00:01.0 PCI bridge: Intel Corporation Xeon E3-1200/2nd Generation Core Processor Family PCI Express Root Port (rev 09)
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
00:16.0 Communication controller: Intel Corporation 6 Series/C200 Series Chipset Family MEI Controller #1 (rev 04)
00:1a.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2 (rev 04)
00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 04)
00:1c.0 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 1 (rev b4)
00:1c.1 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 2 (rev b4)
00:1c.2 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 3 (rev b4)
00:1c.3 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 4 (rev b4)
00:1d.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1 (rev 04)
00:1f.0 ISA bridge: Intel Corporation HM65 Express Chipset Family LPC Controller (rev 04)
00:1f.2 SATA controller: Intel Corporation 6 Series/C200 Series Chipset Family 6 port SATA AHCI Controller (rev 04)
00:1f.3 SMBus: Intel Corporation 6 Series/C200 Series Chipset Family SMBus Controller (rev 04)
01:00.0 VGA compatible controller: NVIDIA Corporation GF108 [GeForce GT 540M] (rev ff)
02:00.0 Ethernet controller: Atheros Communications Inc. AR8151 v2.0 Gigabit Ethernet (rev c0)
03:00.0 Network controller: Atheros Communications Inc. AR9287 Wireless Network Adapter (PCI-Express) (rev 01)
04:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5116 PCI Express Card Reader (rev 01)
05:00.0 USB controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 04)

I'm running a dual boot with Windows 7, sound always works there.

I've tried loading earlier kernels [3.2.0 >] but that hasn't helped.

I've tried playing with alsamixer, unmuting and raising volume, doesn't work

I've tried playing with pauvcontrol, doesnt work. Althought, strangely, when i play a song, under output i can see a bar moving implying that something is working, just the sound isn't getting through my speakers. Thus it might be a hardware problem.

I've tried unistalling and reinstalling pulsaudio annd alsamixer, doesn't work [maybe made it worse...].

I've heard reverting back to kernel 3.0... works, but i'm reluctant to try that[i dont know much about kernels].

Thank you.

Please tell me what other information you need.

EDIT: My audio has started working again after another reboot. However this time im not connected to my external audio on startup. I will see if this is the issue next time i'm at home

Edit: Connecting to external audio is not the problem.