Mac Mini HDMI port no longer working

Hi, OK so their is a bit of a back story to this issue that I will try to explain in as few words as possible.

One day (3 weeks ago) my lush 27" monitor decided to die on me so (the one I had since I bought my Mac mini, connected via its HDMI port using a HDMI cable, no adapters), as it was still under warranty, I sent it back to the manufacturer.

While my monitor was away I had to use an old 14" I had lying around, however, this didn't have any digital ports so had to purchase a mini port to VGA adapter. When this was plugged in it didn't work orginnally, I could access any settings as my Mac booted into the boot options screen. So I did a load of random things resetting PRAM and various others I googled and I managed to get it to work.

Now my monitor is back, I plugged in my HDMI cable again, the one I used previously and hadn't used while the monitor was away but all I get is a 'No Signal' error on my monitor when I select the HDMI as the source. I tries all the stuff before like resetting PRAM and other bits but can't get it to work.

My monitor works fine though if I use the VGA port and the adapter, I am using OSX 10.8.4

It's almost as if the system is now only using the Mini port for displays and not any other, any way to reset this or advice, tips or tricks?