where can i download an audio controller for my pc?

Go to the manufacturer's website, look up the model number of your computer, find the drivers for your computer, and look for audio drivers.

Depending on your computer there might be a program installed to automatically download and install the drivers for your computer. Also if your computer came with disks then there is probably one that has drivers on it but those will probably be older than what's on the website. However if you put in the wrong disk it could wipe out your system and reinstall everything so if you list the disk (by name) that came with your computer we can tell you which one your might want to try.

If you tell use the manufacturer and model number as well as operating system of your computer we can try to help you find the drivers.