[MichaelB]

For both of the lights to be out, it can be as simple as a blown fuse for the low beams.

 

[MichaelB]

There is one ballast per lamp. Ballasts are a problem but a bad ballast will effect only one lamp at a time.

The person that installed the HID system may have also installed a headlight cutout relay. You will need to find that modification and test it to make sure power is being supplied.