relationship help.

Kenn
I have been in a relationship for going on 4 years now. We were high school sweethearts and my first real love. He proposed to me 4 months ago and we are planning on getting married in May. 
I feel like the spark is gone. I had surgery and we weren't able to have sex or anything like that for about a month. Today we did it for the first time and I felt nothing. I feel like the connection is gone. I want the spark back. I don't know what to do....I feel so lost and honestly so broken right now.