How can I use Kernel 3.19 in 14.04 now?

You can install a newer kernel

• as described in Kernel/MainlineBuilds or

• in this case more simply with the packages built from linux-lts-vivid from the trusty-updates repository:

  sudo apt-get install linux-generic-lts-vivid
  

  This meta-package always depends on the most recent version of Canonical's v3.19 kernel branch.

  The equivalent for the v4.4 kernel branch of Ubuntu Xenial is linux-generic-lts-xenial (what a surprise).

Since kernel packages of different branches don't replace each other, there is virtually no danger, that either of the above steps will make your system unbootable¹. If the newly installed kernel doesn't run, you can select to boot different/previous kernels in the GRUB menu during boot.

¹ The most notable exception is a broken GRUB configuration. If update-grub (called by the kernel package post-installation and post-removal scripts) doesn't work without the new kernel, it won't work with the new kernel either.

You can now install the "latest" (3.19) Ubuntu kernel directly from the repositories:

sudo apt-get install linux-image-generic-lts-vivid linux-headers-generic-lts-vivid

This will install stable Ubuntu kernel for Vivid. And the headers that are needed for building several modules on your system.

Hope this helps!

The easiest way to upgrade kernel to 3.19 in Ubuntu 14.04 is to run:

sudo apt-get install linux-generic-lts-vivid

This will install meta package, that will pull everything else. Image and headers will be installed.

This method is good, because 3.19 kernel will get security updates and bug fixes through routine update & upgrade process.

Old kernels 3.13 or 3.16 will not be removed. They will be bootable using grub menu. And they will get updates too.

If you do not want 3.13 or 3.16 kernel to be updated, you can remove meta packages:

linux-image-generic linux-headers-generic for 3.13

linux-image-generic-lts-utopic linux-headers-generic-lts-utopic for 3.16