At least based on dxdiag, It looks like the drivers are installed correctly. When you reinstalled them, did you try first uninstalling the old drivers from Ctl Pnl->Programs and Features. (if not you might try that as well)

As to your questions about the devices you're seeing in Device Manager

Are you really seeing an item titled NVIDIA High Definition Audio in Device Manager? I see Nvidia in dxdiag as your integrated graphics card (not sound)

fyi, for Hi Def Audio (which you have) connections are as follows (where Windows only talks to the Audio Controller. The Audio controller connects to all audio devices on the sound card)

Windows <==> Hi Def Audio Controller <==> Sound Card

Audio Controller
You should be seeing High Definition Audio Controller listed under DvMgr's System Device category (the code box snippet below is from your dxdiag report)

Code:

(     Name: High Definition Audio Controller
Device ID: PCI\VEN_8086&DEV_293E&SUBSYS_02051025&REV_03\3&11583659&0&D8
   Driver: C:\Windows\system32\DRIVERS\hdaudbus.sys, 6.00.6002.18005 (English),

Sound Card
The Realtek High Definition Audio Devices you see in DevMgr under Sound category are all devices located on the Sound Card

Also looks like the mic driver is installed OK as well so i don't have any other good answers as to your problem

Code:

---------------------
Sound Capture Devices
---------------------
            Description: Microphone (Realtek High Definition Audio)
  Default Sound Capture: Yes
  Default Voice Capture: Yes
            Driver Name: RTKVHDA.sys
         Driver Version: 6.00.0001.5802 (English)

Thank you for taking the time looking through my problem.
Though nothing seems to help. My computer have been like this for a while now, i have lots of tiny problems and such which none of them have a good explanation
I discovered now that at least i can use a microphone connected through bluetooth... though, the sound recorded through that is horrible.

And yes, there really is a device in the device manager called NVIDIA High Definition Audio

Oh. It just occurred to me what that device is: You must have an HDMI port on laptop? That Nvidia HD audio device would support your laptop's audio out over HDMI

Unfortunately, that wouldn't be related to your mic problems tho. As i believe your sound capture is being supported by the Realtek driver.

You're probably outside of any Acer warranty i'll guess..

Of course, it's for the HDMI!
Yes, sound capture is supported by Realtek. As i said, there is no logical explanation to why my computer is acting up like this.
I'll contact Acer and hear what they say. I've only had my computer for 19 months so maybe it still has some warranty.