SCREEN OF DEATH

Spent some time tonight editing an entry for Flower Friday for a change but hit a problem on my Mac when I went to upload, cutting a boring story short I seem to be faced with 'The White Screen of Death' and can't get the darn thing to boot up now, given up until the morning (looked it up, need to repair disc in disc utility!!!!!). I'll need to put my technical head on before I attempt to fix it.