Mic won't work after Win 7 install

I have an HP Pavilion dv9812us Entertainment PC that had Vista Home Premium 32-bit installed on it. I performed a fresh installation of Windows 7 Pro 64-bit on it, and ensured that all Windows Updates and HP drivers were installed. Unfortunately, I do have one problem as a result of this upgrade. The mic jack does not seem to work. The built-in mic works just fine, and I've tried different mics on this and other computers, just to confirm that it wasn't a problem with the mic. However, whenever I plug the mic into the mic jack on the HP, it simply doesn't appear in the "Recording" tab under the "Sound" menu. I've checked to ensure that all disabled and disconnected devices are also visible, and I've downloaded the Realtek Audio Manager from their website. I also downloaded the latest audio drivers from HP's support site, and ran DriverMax to ensure I had the latest drivers. Yet despite this, Windows will not recognize any mics besides the built-in one.

I also found that HP does not support Win 7 on this particular model, so while I have downloaded the Vista 64-bit versions that are offered, I'm not sure if they will work with the 7 installation that I have now. I'm completely stumped - and any advice would be most appreciated!

Not sure if this will help as you may have problems with your drivers. Maybe you should try plugging your mic on another jack. If you plugged it on the front pink jack, try plugging it on the rear pink jack or vice versa.

On the list of your Recording Devices, right-click an empty space and make sure that "Show Disconnected Devices" and "Show Disabled Devices" are checked.

Thanks everyone for your replies! Good dog, stormy13! Thanks for catching that typo - I fixed it now. Should have been 9812us, not 8912us! I have used the HP Update and HP Support Assistant, John47 - unfortunately with no luck - but thank you for the suggestion.

I have indeed checked the "Show Disconnected Devices" and "Show Disabled Devices" options, Vertex - an excellent idea. Sadly, there is only one mic jack - the front one. The other two front jacks are for headphones. I just find it very curious that the built-in mic works, but Windows simply will not pick up a mic attached through the mic jack. I wouldn't be surprised if it were some sort of a device driver issue with this particular HP model and the lack of Win 7 support provided for it.

If your mic should display in there, enable it first by right clicking it and choosing Properties then "use this device".

OK, right-click on the speaker icon on the side panel of the Taskbar. And choose Playback Devices, then follow the directions on the first screenshot in the left. Make sure the volume for "Microphone" is not zero or muted so adjust it to 100.

Then right-click on the speaker icon on the side panel of the Taskbar again. this time choose Recording Devices, then follow the directions on the second screenshot.

Check your mic if you hear anything.