LG V692wk won't play DVDs

Question

LG V692WK will no longer play DVDs -

We played a new store bought Region 4 ( AUstralia) DVD one night - worked fine - kids went to watch it again and it didn't work - Now no DVDs are loading - we only see the "loading/reading" box which eventually dissapears from TV screen and then disc stops spinning and ejects. Please help.

I have checked manual - we have unlocked Ratings and are at a loss as to what could have caused this.