Now I'm very aware that there are many questions out there that are quite similar to what I'm experiencing, but I have looked through many and I have not found a suitable answer. You are welcome to suggest questions that are similar, but I doubt that it will help. Getting on to the issue at hand, whenever I do anything that involves installation, whether it be codecs for videos, new programs or whatever the latter, I always get the 'Dependencies not met' error. In addition, I also get this notification in the panel:

When clicked, the menu says this:

"An error occurred. Please run Package Manager from the right-click menu or run apt-get in a terminal to see what is wrong. The error message was: ' Error: Broken Count > 0'. This usually means your installed packages have unmet dependencies."

It gives me three items to click:

1. Show Updates
2. Install all updates
3. Check for Updates

And then finally:

1. Show Notifications (with a tick)
2. Preferences

When I try 'Install all Updates' (also Check Updates > Install) it says this:

and also this:

As well as 'Ubuntu has experienced an internal error' and 'Did this error occur when moving from one version of Ubuntu to another?' (I clicked NO, because it didn't).

So I took it's advice and ran sudo apt-get install -f

This is what results:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Correcting dependencies... Done
The following extra packages will be installed:
  libapt-pkg4.12:i386
The following packages will be upgraded:
  libapt-pkg4.12:i386
1 upgraded, 0 newly installed, 0 to remove and 87 not upgraded.
1 not fully installed or removed.
Need to get 0 B/941 kB of archives.
After this operation, 0 B of additional disk space will be used.
Do you want to continue [Y/n]? Y
E: Internal Error, No file name for libapt-pkg4.12

When running sudo apt-get update it's all fine, but running sudo apt-get install -f still results in the same thing.

I really have no idea what to do... can anyone help me?