I can´t save my worksheet

I was working on my worksheeet and I managed to save it about 4 times during the process but at the end I couldn´t save it. I just click on the button but nothing happen. It took me 2 hour to do my worksheet and now I am so disappointed not to able to save it. 
Last week there was the same problem and I lost all my answers, I dont want it to repeat, Please fix the problem