Actually you do not compile the kernel module. Nothing is required on your
part. It just happens when you change drivers. Ubuntu uses dkms which should
silently take care of any changes that you make. However, you can mess
things up if you change from the default kernel and changes to the driver
may not work with an older kernel and vice versa.

I have had this happen on Ubuntu in the past year. I update the kernel and
it works fine. If I try to boot a previous kernel which shows in grub, the
graphics go back to plain vanilla. It sounds like the reverse is happening
here and for some reason the new kerenl is not working with the driver.
Switching to a previous kernel from grub may restore things. It is not a
permanent solution because you want to use the latest kernel. This is the
main reason why kernels do not get many upgrades with a version and do not
go beyond patching the existing kernel to fix a vulnerability and the like.