Biggest Client won't return my phone calls!

I was unexpectedly fired from my previous firm. That day I reached out to other local firms that had interest in having me come to their firm.  Long story short with the timing of all the winter holidays it took WAY longer (3 months) than expected to get on at my new firm.

That first week after being let go I had reached out to all my clients and told them I was no longer with the former firm and was moving to a new firm.

This #1 client is actually the sponsor of a 401k I managed for a dental office. This client was my family dentist ever since I was a kid and after a couple years in the investment business became one of my biggest clients. 

I KNOW that the old firm was trying to solicit my client to stay with them (even brought Christmas treats for his whole office right before the holidays). I know this because my client told me so.  My client did not want to remove the old advisory firm from the 401k since I had yet to move to a new firm.

There was a lot of time with little communication (in hindsight a mistake, but there wasn’t really anything to update him on). I tried calling his personal cell phone twice this week and left a message the first time. Absolutely no response.. (2nd phone attempt was on his day off)

Any suggestions on how to open up this relationship again would be GREATLY appreciated. 

Thank You