problems in search engines

Four days ago I had changed the date of some old articles on my blog. I realized that in the following days the traffic of views given by jetpack is practically non-existent.jetpack support told me that before my traffic came mainly from google.it, but now they don’t see any search anymore … In my permalinks the date wasn’t there, so I don’t know what the cause could be. Thanks for your help.

The page I need help with: [log in to see the link]