VirtualBox problem: Kernel module is not loaded

First make sure you have these packages installed:

$ sudo apt-get install dkms build-essential linux-headers-`uname -r`

If installing the above does not solve the issue you might have a kernel version greater than 4.4.0-20 which enforces that unsigned kernel modules are not to be allowed to run with Secure Boot enabled in BIOS. In this case you can do one of the following:

• Disable Secure Boot in your BIOS settings

OR

• Sign the VirtualBox modules as described in this post https://askubuntu.com/a/768310/94759

After run this command, my VirtualBox is working:

sudo apt install -f

sudo apt-get install --reinstall virtualbox

...is what did it for me. Hope this helps!

This command worked for me

sudo /etc/init.d/vboxdrv setup

Next I got following error

The VirtualBox VM was created with a user that doesn't match the
current user running Vagrant. VirtualBox requires that the same user
is used to manage the VM that was created. Please re-run Vagrant with
that user. This is not a Vagrant issue.
The UID used to create the VM was: 0
Your UID is: 1000

That got solved by running vagrant up command with root access (sudo).

this should fix the issue with VirtualBox Version: 5.1

Just install linux-headers and run vboxconfig again

#> sudo apt-get install dkms build-essential linux-headers-`uname -r`
#> sudo /sbin/vboxconfig