Sando

Hi mates, I'm not at the same point of you at all, but I experienced something I was going to beat RED at the Mt. Silver 3F and I saw Raikou in the corner. I wasn't aware of the Celebi quest, and go away without talking to him (I was afraid of a fight at this moment) And now, Raikou, left the place and I can't find him anymore. What can I do ? thank you