This should have been the one that you tried: https://downloadcenter.intel.com/download/19199/Audio-SoundMAX-Audio-Driver.
If this is not working, first thing I would suggest is for you to try loading the previous version: https://downloadcenter.intel.com/download/18355/Audio-SoundMAX-Audio-Driver.
Tried both of those and neither of them will install, keeps saying my hardware isn't supported and if i've unistalled the audio drivers to restart and try the install again. Done if a fair few times on both the newest version and older versions and each time get the same thing.
I have no sound tab in Device Manager which suggests NO audio drivers are installed at all hence why the onbaord isn't getting seen. Tried windows update and that doen't give any downloads for Audio.
I've borrowed a sound card and installed that which works but once removed still have no onboard sound at all as it thinks there isn't any.
In regards the Audio issue with the Intel® Desktop Board DQ45CB, please verify if you are using the latest BIOS version 0133.
Then, please follow these steps.
1-Uninstall and delete the current Audio driver from device manager
2-Restart the computer, download and run the Intel® Chipset Device Software for Discontinued Intel® Desktop Boards driver then, the Intel® ME: Management Engine Driver for Intel 4 Series Chipset-Based Desktop Boards, finally restart the computer.
3-Install latest Audio driver: SoundMAX* Audio Driver
Download Audio: SoundMAX* Audio Driver
Hopefully, the troubleshooting will solve the issue.