how old is your domain / site?
Normally, losing all traffic is not normal, but sometimes, for new sites google sends traffic to them during the first 2-4 weeks of their existence, and after that the sites completely vanish from the SERPs, so in this regard it COULD be normal (if your domain is less than 1 month old). That's why I asked...
But if your domain and site are months old you've just been hit by google update, but I don't think you should do anything about it just yet as I just saw some people started recovering their traffic, so it might happen to you too in the coming (5-10) days...