Fixing sound after upgrading to Ubuntu 9.10 Karmic Koala

I recently upgraded from Ubuntu Jaunty (9.04) to Karmic (9.10), and the sound stopped working. As a matter of fact, no sound card was detected. Searching around, it turned out that the problem lied with a wrong kernel version, which actually stems from an apparent bug in the new grub boot loader that ships with Karmic. Even though I’m using Ubuntu, this might affect other distributions that use the same boot loader. If you face a similar problem, try the following:

First, check your kernel version:

• sudo uname -r

If you see a version below 2.6.31, do the following:

• Delete your old /boot/grub/menu.lst file. Due to an apparent bug, grub will not overwrite it during distribution upgrade or subsequent upgrade-grub commands.
• Run sudo update-grub. A new menu.lst will be generated, now pointing to the right kernel.
• Install grub on your MBR. First make sure which device holds your MBR (most probably /dev/sda, but it might be /dev/hda if you have an old IDE disk), then run: sudo grub-install /dev/sda (replace with the proper device)
• Reboot.

Hope this helps.