Gateway ec18 no sound in windows 7 or windows vista

Hi, I have a Gateway EC18 series notebook. i currently cannot get sound to come from my internal speakers, though headphones work fine. I have done a factory restore several times, reinstalled windows (both vista and 7) several times, updated all the drivers, checked to make sure nothing is muted, and I still have no sound. Any ideas? By the way, the sound card is a Realtek HD Audio. Thanks for the help.

specs of computer are as follows:

Specifications
Part Number: EC18Gateway EC18 Notebook Series
Following are the specifications for the Gateway® EC18 notebook series.
Specifications are subject to change without notice or obligation.
Feature Specification Operating System1 Genuine Windows Vista® Home Premium (Service Pack 1) Processor1 Intel® Core™2 Solo processor SU3500 (3 MB L2 cache, 1.40 GHz, 800 MHz FSB, 5.50 W), supporting Intel® 64 architecture Chipset Mobile Intel® GS45 Express Chipset Memory1, 3, 4 Dual-channel DDR2 SDRAM support
Up to 2 GB of DDR2 667 MHz memory, upgradeable to 4 GB using two soDIMM modules (for 32-bit OS) Video Subsystem Mobile Intel® GS45 Express Chipset with integrated 3D graphics, featuring Intel® Graphics Media Accelerator 4500MHD (Intel® GMA 4500MHD) with up to 1759 MB of Intel® Dynamic Video Memory Technology 5.0 (64 MB of dedicated video memory, up to 1695 MB of shared system memory), supporting Microsoft® DirectX® 10
Dual independent display support
16.7 million colors
External resolution/refresh rate:

• 2048 x 1536: 75/60 Hz
• 1920 x 1440: 85/75/60 Hz
• 1920 x 1200: 75/60 Hz
• 1920 x 1080: 100/85/75/60 Hz
• 1680 x 945: 100/85/75/60 Hz
• 1600 x 1200: 120/100/85/75/60 Hz
• 1600 x 900: 120/100/85/75/60 Hz
• 1400 x 1050: 85/75/60 Hz
• 1366 x 768: 85/75/60 Hz
• 1280 x 1024: 120/100/85/75/60 Hz
• 1280 x 960: 85/75/60 Hz
• 1280 x 768: 85/75/60 Hz
• 1280 x 720: 100/85/75/60 Hz
• 1024 x 768: 120/100/85/75/60 Hz
• 800 x 600: 120/100/85/72/60 Hz

MPEG-2/DVD decoding
WMV9 (VC-1) and H.264 (AVC) decoding
HDMI™ (High-Definition Multimedia Interface) with HDCP (High-bandwidth Digital Content Protection) support LCD Properties 11.6" HD 1366 x 768 pixel resolution, high-brightness (200-nit) Gateway Ultrabright™ LED-backlit TFT LCD, supporting simultaneous multi-window viewing
16:9 aspect ratio Hard Drive1, 7 250 GB, 320 GB, or larger hard disk drive Media Card Reader Media card reader supporting:

• Secure Digital™ (SD) Card
• MultiMediaCard (MMC)
• Reduced-Size Multimedia Card (RS-MMC)
• Memory Stick® (MS)
• Memory Stick PRO™ (MS PRO)
• xD-Picture Card™ (xD)

Optical Drive No optical drive Audio Optimized 2nd Generation Dolby Sound Room®5 audio enhancement, featuring:

• Dolby® Headphone
• Dolby® Natural Bass
• Dolby® Sound Space Expander

Two built-in stereo speakers
High-definition audio support
S/PDIF (Sony/Philips Digital Interface)10 support for digital speakers
Built-in microphone
MS-Sound compatible Peripheral Subsystem Integrated high-def webcam
5-in-1 card reader , supporting MMC, SD, xD, MS, and MS PRO cards
Built-in microphone
Three USB 2.0 ports
HDMI™ port with HDCP support
External display (VGA) port
Headphone/speaker/line-out jack with S/PDIF support
Microphone-in jack
Ethernet (RJ-45) port
DC-in jack for AC adapter Communication WLAN1, 2: Intel® WiFi Link 5100/5300 (dual-band quad-mode 802.11a/b/g/Draft-N) Wi-Fi CERTIFIED® network connection, featuring MIMO technology
WPAN1: Bluetooth® 2.1+EDR (Enhanced Data Rate)
LAN: Gigabit Ethernet, Wake-on-LAN ready
WWAN1, 2, 8: UMTS/HSPA at 850/900/2100 MHz and quad-band GSM/GPRS/EDGE (850/900/1800/1900 MHz) upgradeable to 7.2 Mb/s HSDPA and 5.7 Mb/s HSUPA supporting receiver diversity and equalizing at 2100 MHz (for 3G models). Optional support for receiver diversity and equalizing on 2100 MHz Keys and Controls1 84-/85-/88-key keyboard
Multi-gesture touchpad pointing device, supporting:

• Circular-motion scrolling
• Pinch-action zoom
• Page flip

10 function keys, four cursor keys, Windows® key, international language support
Power button with LED
Easy-access switches with LED1: Bluetooth®, WLAN/WWAN Power 62.16 W 5600 mAh 6-cell Li-ion battery pack with 8-hour battery life8
Gateway PowerSave 3-pin 30 W AC adapter
ENERGY STAR® 5.0 Dimensions
(W × D × H) 11.22 × 8.03 × 0.87/1.18 inches (285 × 204 × 22.1/30.0 mm)
2.97 lbs. (1.35 kg) with 6-cell battery Software10 Gateway Identity Card
Gateway Recovery Management
Gateway wallpaper
Gateway screensaver
Microsoft® Works 9 with Office Home and Student 2007 Trial
Microsoft® Windows Live™ Essentials Wave 3
Norton Internet Security™ 2009 (60-day trial)11
Google Desktop™
Google Toolbar™
Google™ Setup1
Adobe® Reader®
Adobe® Flash® Player 10
CyberLink® PowerDVD™
CyberLink® Power2Go™ 6.0
WildTangent® Other Color Options:

• NightSky Black
• Cherry Red

Optional items:

• Protective bag
• 6-cell Li-ion battery pack
• 3-pin 30 W AC adapter
• Mouse

yes, realtek hd audio; however, i've tried both the realtek driver and the microsoft one to no avail. windows does not detect a problem at all, but still no sound. i've used the vista and windows 7 drivers from Gateway Official Site: Notebooks, Laptops, Desktops, All-in-Ones, Displays, Monitors, Accessories, but nothing helped.

hi,
i got the same little notebook for travel and i didn't use it last 3 months (no travels :) )

and now i have the same problems... no any sound... with the same Realtek Hd.
i've tried both the realtek driver and the one from Gateway site and no luck.

if you have any suggestions, please help.
thank you!