My best manager left my current (and first ever) employer one year ago. I had very strong professional and friendly relations with him and he promoted me for the first time to a managerial role. After he left, there was some re-organizing at the company and I lost some of my status in that process. As a consequence I want to look for other opportunities and wanted to use him as my reference. However, I have tried contacting him for ages and he hasn't responded. I felt it would be wrong to continue pestering him.
Partly I am puzzled as to why he is unwilling to even communicate me, but my question is - what can I do when the best person who could give me a reference... doesn't?