Suddenly lost sound after Nvidia Geforce install

[tamethegamer]

So I have completely lost all audio on my Windows 7 machine after installing the Nvidia Geforce Experience and additional drivers.

The version of Nvidia Geforce Experience is: 2.5.12.11
The version of the Nvidia HD Audio is:
1.3.34.3

Things I have done to fix this:
-Uninstall Geforce Experience and all the drivers (including the HD audio one)
-Checked AVG's virus vault for any files that may have not been downloaded for protection (no files here)
-Double checked my Logitech Z506 speakers are all correctly plugged in and working (these are brand new too)
-Restarted computer
-Checked my speakers are the default audio output
-Disabled other audio outputs other than my speakers
-Attempted to rollback driver version (option greyed out and couldn't be done) and update driver (which resulted in an alert saying the best driver option is already installed)

UPDATE: After installing Realtek audio I have managed to gain audio back but only if i plug my headphones in.

It should be noted that there was sound before this download and install earlier today. This is why I highly doubt that it is anything but an Nvidia Driver issue.
Could anybody help me out?

 

[MasterDell]

What cord is connected to your monitor?

And so headphones work and speakers don't?

 

[tamethegamer]

What cord is connected to your monitor?

And so headphones work and speakers don't?

I am using a displayport to mini display port from my GTX 970 to the Dell Ultrasharp U2414H

And after installing Realtek, yes, the headphones work but the speakers do not. Bear in mind these speakers are brand new and have been working perfectly fine in the 5.1 config for around 3-4 days until now

 

[MasterDell]

So just to be clear, you are plugging in your headphones and they work great. Then when you unplug your heaphones and then plug in the speakers to the same jack, they don't work?

 

[tamethegamer]

So just to be clear, you are plugging in your headphones and they work great. Then when you unplug your heaphones and then plug in the speakers to the same jack, they don't work?

Not quite.
I have the Logitech Z506 5.1 surround sound set which occupies the line out (green), c/sub (orange) and rear (black) audio ports out the back of my motherboard.
I plug my headphones into the front green line out port and they work.

Either way, with my headphones plugged in or not, the sound isn't coming out of the speakers even though in the sound options it is recognizing the sound.

Edit: I know that when you plug in headphones in the front, the rear output is muted.

 

[MasterDell]

So do the headphones work when plugged in the back?

 

[tamethegamer]

So do the headphones work when plugged in the back?

yes

 

[MasterDell]

That's super weird.. Maybe try like some cheap speaker(s) and see if that works.