Help!! Sketch Software will not load up on my Laptop

Hello,

Up till a few days ago, my Arduino sketch software was working perfectly, but all of a sudden, it will not load up. Confused by this I decided to download 1.6.4 version, this was successful, I clicked on the Arduino desktop Icon, the Arduino Icon start page started, the command line at the bottom read "loading configuration" then "initialising packages" then “Starting” it seems to stall on this and eventually disappears / crashes ?? I do not what has happened, I am not a computer whiz ! my laptop is a Toshiba Satellite C50B

Can you help me ?

Regards

Ray