Recover an unfinished Excel document

Question

I would be most grateful if anyone can help me as soon as possible. I was working on an Excel document which had been sent by email to me to complete. I am sure that I pressed save but it has simply disappeard and is not in my documents. It would take hours for me to do this work again as I was copying and pasting from websites which took a long time to research, so your help is very much needed. As I am a PC beginner, it would be appreciated if you would be so kind and send me very basic and easy to follow instructions step by step.
Thanking you in anticipation of a response at your earliest.