PS4 locked to wrong region

[GeeTeeUK]

I've had a UK PS4 for about a year now and it has been working fine. I installed the latest update at the weekend and then played a DVD yesterday. This may have been the first DVD I've played in the machine as I was prompted with a 'You must set a region to allow playback' message, to which I selected Region 2 for Europe.

Tonight I've tried to play a BD and it has come up with the following message:
"ATTENTION
This disc has been coded for Region B only and will not play in this machine.
Please eject this disc and play on a Region B player."

I tried another Region B-locked disc and got a similar message.

Has anyone had the same thing happen, or knows how to chage it back? I didn't even realise you could alter the BD Region - I certainly can't find any setting within the options.

Can anyone help?

Apologies if this is the wrong forum but as it was regarding BD playback rather than gaming I thought this more appropriate.