We can all relate to this. It either happened, or we've feared it happening:
Yesterday, All those backups seemed a waste of play. Now my chapters have all gone away. Oh I believe in yesterday. I...pushed...something wrong What it was I could not say. Now my thesis is gone and I long for yesterday-ay-ay-ay. Suddenly, There's not half the files there used to be, And there's a deadline hanging over me. Office crashed so suddenly. Yesterday, The need for back-ups seemed so far away. I knew my thesis was all here to stay, Now I believe in yesterday.