Sketch Up Model Went Completely Blank/White

Technical Problems
1

Help!
I was working on a model in SketchUp and suddenly it went blank, when I reopened it, it seems that the components are listed and the file size is 58MG, but the actual model is completely white and blank! Can anybody help me? What did I press?!

Please help!

2

CMD-A and Delete? Or have you only messed up the camera position? What does the Entity Info say if you select all (CMD-A)?
Have you checked if the backup file is OK?