What's your problem?acer ali m5451multimedia audio Driver

Have you tried to see if microsoft can find a compatible driver?
Go into device manager, open Sound Video Game Controllers and select your device. Right click it and select update driver, then select Search Automatically for it.Hope this helps.

The obvious, is it muted? NO. Disable device in Device Manager, enable device, no change, uninstall audio device, reboot, I don't know your OS, your OS should automaticly ID the audio an add driver. If it does not go to Acer website a download audio driver for your OS. Install manually. You stated,"after installing a hard drive I had from another laptop" . The Harddrive you installed, did you format it and install into this laptop and clone the drive? I am a bit confused by the statment, "after installing a hard drive I had from another laptop"?

Download AND install the audio driver, appropriate for your laptop, and Operating System.

http://support.acer.com/us/en/product/default.aspx?tab=1&modelId=556

Top audio driver file is for Windows Vista, 32-bit or 64-bit
It's a Zip file.
(Version 6.0.1.5643)

Second audio driver listed is for Windows XP, (Home or Pro), and 32-bit.
(Version 5.10.0.5643)

If you do not know how to download AND install the appropriate audio driver file, post in a Comment.

Driver: Small piece of software that allows the Operating System to communicate with a device.

Device in question is the audio chipset.
Don't know what the O/S is you didn't state.

Regards,
joecoolvette

(After installing the audio driver file, restart your computer if not asked to do so )

Download the Audio Driver: http://global-download.acer.com/GDFiles/Driver/Audio/Audio_Realtek_6.0.1.5882_W7x64W7x86_A.zip?acerid=633921208653441502&Step1=Notebook&Step2=Aspire&Step3=Aspire%202930&OS=721&LC=en&BC=Acer&SC=PA_6

Download the Webcam Driver: http://global-download.acer.com/GDFiles/Driver/Camera/Camera_Suyin_3.0.7.2_W7x64W7x86_A.zip?acerid=633921201853346404&Step1=Notebook&Step2=Aspire&Step3=Aspire%202930&OS=721&LC=en&BC=Acer&SC=PA_6

Hello bradleymarr
You can download your product from this place . It's free :
http://download.cnet.com/ALi-AC-97-Audio-Controller-SigmaTel-Codec/3000-2110_4-130433.html
Available only up to Windows XP .
Best regards,
fanaudi .

try this
http://download.cnet.com/ALi-Audio-Accelerator-WDM-Driver/3000-2110_4-197164.html

uninstall the audio driver and use this link for acer audio driver.

Acer Europe - Service & Support, Drivers & Utilities

The driver might be corrupted. Try downloading the one from Acer's website. They should have available free downloadable driver for your audio and video devices. Click here to check for drivers.

FM Solutions - We are Specialized in ACER LAPTOP Service and Repair.

FM Solutions:
1'st Floor Sanali Mall, MC Donald Building,
Opp Chermas ABIDS - Hyderabad.

Call 09700069594 / 9705009788

Hi there
Get the sound drivers here:

http://support.acer-euro.com/drivers/notebook/as_4315.html

Good luck and kind regards