apt-get dist-upgrade does nothing when trying to upgrade from wheezy to jessie

apt-get dist-upgrade does nothing because your system is already up-to-date… for wheezy. You've instructed your system to follow wheezy, and that's what it does. To upgrade to another release, you need to change your package sources to point to that other release.

Package sources are declared in the file /etc/apt/sources.list. Edit this file and change all references to wheezy into jessie. Also edit files under /etc/apt/sources.list.d in the same way, if you have any.

You can make upgrades follow releases automatically by writing stable instead of e.g. wheezy, but this is not recommended because you'll get a whooping big upgrade each time a new stable release comes out, whether you're ready or not. Using moving release targets is mostly useful for testing.

Once you've updated /etc/apt/sources.list, run apt-get update to read the list of available packages for the release that you are now targeting, then apt-get dist-upgrade to perform the upgrade.

This is covered in the upgrade notes under “Preparing sources for APT”. It's a good idea to review the upgrade notes before you perform the upgrade. (Switch to the right architecture if you aren't on a 32-bit PC.)

Open the terminal and type the following command:

sed -i 's/wheezy/jessie/g' /etc/apt/sources.list
apt-get update
apt-get upgrade
apt-get dist-upgrade
apt-get autoremove
apt-get clean
apt-get dist-upgrade -f
reboot