"Doesn't work" covers a lot of territory. Will the software launch? Does it stutter? Is the screen at the correct resolution and frequency (refresh rate) now.
Before you do anything else, I think you should remove the driver to the 5450 card first, and let Windows go on the web to find the correct driver for the IGP, (or APU, whichever we're deciding to call it).
Keep in mind, "once upon a time", and video driver issue would cause a "stop error". otherwise known as "the blue screen of death" (or "BSOD" for short.
If the integrated graphics offers HDMI output(s), then you need a separate driver specifically to work that. It is comprised of a combined video AND sound driver, to allow the HDMI connection to provide throughput of sound and video via HDMI.
To expand on that, without the HDMI sound/video driver, you could use an adapter to change the DVI output to HDMI, but there would be no sound.
BTW, why you want to use a VGA video connection is, (to be tactful), perplexing.