[Spyro9977]

I'm currently running a Compaq Presario V4000 (Old, I know) and suddenly it's sound has dissappeared. I found a forum, saying 'use cmd...' but when I try to use the cmd and type in '..', it comes up with 'Class Not Registered.' I'm not a techno nerd or anything, so I can't really describe what my computer is running or anything. But there's no sound, at all, when I go into the sound and audio box in control panels, the sound playback, and sound recording are grayed out, and when I try and fix it, it comes up with the message 'Class Not Registered'. Help would be very appreciated.

[Mark1956]

Have a look in the Device Manager and see if there is a yellow warning next to any of the devices.

Click on Start > Control Panel > System > Hardware > Device Manager.

[Spyro9977]

I can't even open the Device Manager. I can get into System, Hardware. But I can't get into Device Manager because it says 'Class Not Registered'.

[Mark1956]

Do you have a Windows XP disc and is all your important data backed up?

[Spyro9977]

No, I don't have a Windows XP Disc, because I got it ages ago from my father. My data is backed up, but I don't have a hard drive.

[silvernoodles]

There seems to be a serious issue. Can you try & repair your OS.
Also as suggested by Mark1956, have your important data backed up.

[silvernoodles]

Not too sure but is this of some help:
http://www.free-codecs.com/guides/Ho...0154_error.htm

[Spyro9977]

Sorry, but it doesn't work. How do I try and repair my OS?

[Mark1956]

To repair the OS you need a copy of XP that is an exact match to your installed OS and at the same service pack level. Is there a sticker on the PC with the licence key on it?

I would first try to use System Restore and see if that works, if not then you will have to borrow a copy of XP (they are no longer for sale).

XP System Restore Guide

I would also suggest running a test on the hard drive to make sure it is healthy. If a failing hard drive is the cause of the problem then it will need to be replaced before you can go any further and you will need a copy XP to reinstall the OS.

Do you know if the hard drive has a Recovery partition?

Identify the make of your hard drive and then use one of the links below to get the manufacturer's diagnostics for ISO (CD) not the one for Windows.
When the download is complete right click the file and select Extract Here and burn the image to a CD.
In Windows 7 right click the extracted file, select Open With, then select Windows Disc Image Burning Tool then follow the prompts. For all other versions of windows (if you do not have an ISO burner) download this free software. ImgBurn
Install the program and start the application. Select the top left hand option to burn image file to disk and then on the next window click on the small yellow folder icon and browse to the file you have downloaded from the links below. Then click on the two grey discs with the arrow in between (bottom left) and leave it to complete the operation.
Boot the PC into the Bios setup and set the CD/DVD drive to 1st in the boot sequence. Insert the disk in the drive then reboot and the disc will load into dos.
Excelstore Use EStest CD image
Hitachi/IBM Use the Drive Fitness Test - CD Image.
Seagate, Samsung, Maxtor & Quantum Follow links for SeaTools
Western Digital
Toshiba/Fujitsu
If you have a Toshiba/Fujitsu hard drive I would suggest the use of the diagnostics from the Seagate link as this will work on all makes of drive and on any OS.

[SUEOHIO]

If all else fails you can possibly contact compac and see if there is restore/recovery disks for that model of computer. In most cases they run about 30 dollars.And yes you can still find copies of windows xp on the internet. Just be careful who you buy them from though.

[Mark1956]

As production of Windows XP was stopped in June 2008 finding a "legal" copy is extremely unlikely.

If the hard drive on your PC is in its original state there should be a Recovery Partition on it, keep tapping the F10 key at boot up and see if you get the option to Restore to Factory Settings. Be aware this will wipe out everything on the drive. There is also a built in facility to create your own set of Recovery discs, see this guide for the details.

http://h10010.www1.hp.com/ewfrf/wc/document?cc=us&dlc=en&docname=bph08097&lc=en&product=434655

I would still advise you to complete a test on the hard drive before you go down this road. You may still be able to create the Recovery discs even if the Windows partition is showing faults. If the drive has to be replaced you will need those discs, as far as I can tell (without using the service tag number) HP no longer supply them. The other option is to clone the Recovery Partition onto a new drive.