I lost all my data for the last two years in Garmin Connect? Why? Solution?

3375117 said:

I lost all my data for the last two years in Garmin Connect? Why? Solution?

There are basically two possiblities I am aware of:

1. You are logged into a different account than originally (you mistakenly used the button Sign Up, instead of Sign In)
   
   
2. You disabled the permission to Garmin for storing your data. It is in User Settings » Privacy Settings » Storage & Processing.

The solution for the first case is simple - sign out and then sign in back with your original credentials. If that alone does not help, then follow the instructions in the hint #3 of the Troubleshooting guide for (some) data missing after syncing, 

In the second case, if you removed the permission to store your data recently (in the few last hours), then you can still perhaps restore it by re-enabing the permissions. However, if it is more than 24 hours, then the data is gone - Garmin cannot keep the data without your permission.