This question already has an answer here:
I tried doing this
Optional command for temporary root privileges. So you won't need to keep typing sudo.
$ sudo su
enter password. (Note. This is not required, you can continue to use sudo, if you choose.)
First step, make sure your current Ubuntu Version's installed packages are up to date.
$ sudo apt-get update && dist-upgrade
Y when prompted
After that finishes...
$ sudo apt-get install update-manager-core
$ sudo do-release-upgrade
But it brings me this error 'The package 'linux-headers-3.13.0-generic' needs to be reintalled, but it is impossible to find some appropriate archives'