VirtualBox does not work after upgrade Ubuntu

Note: Ubuntu users might want to install the dkms package (not available on Debian) to ensure that the VirtualBox host kernel modules (vboxdrv and vboxnetflt) are properly updated if the linux kernel version changes during the next apt-get upgrade.

If you don't install dkms (before a kernel upgrade), you will have to run

 sudo /etc/init.d/vboxdrv setup