Many people are like your friend: They can point to a definite time when they gave their lives to Jesus Christ and trusted Him alone for their salvation. Sometimes their conversion was very dramatic, although often it wasn't—but in either case they are like the blind man who met Jesus one day: "One thing I do know. I was blind but now I see!" (John 9:25).
But not everyone is like this. My wife, Ruth (who went to be with the Lord only a few weeks ago), grew up in a godly Christian family, and her mother and father taught her about Jesus almost from birth. She sometimes said that she couldn't really remember a time when she didn't love Christ and trust Him as her personal Lord and Savior. Even when times of doubt came, she still knew that God loved her—and that she loved Him.
The real question is this: Are you trusting Christ alone for your salvation right now, and are you seeking to follow Him every day? Remember: He alone is your hope, and He alone is your Savior. The Bible says, "Everyone who believes in him receives forgiveness of sins through his name" (Acts 10:43).
Make sure of your commitment to Christ, and don't let Satan fill you with doubt or fear. The Bible says, "For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life" (John 3:16).