How far back does the Garmin Connect Website retain activities data? My activities are only showing up from 2013 on and I can't see any of my activity data from 2012.
It should go back to the oldest data that you have loaded - if Garmin are not holding that or plan to delete it then they run the risk of having a lot of seriously upset customers. My data starts in Jan 2012 and runs to today - so unless YOU have deleted it it should be there. I would suggest that you contact Garmin support asap and get them to find your data.
Because I innately don't trust anyone to look after my data I store it in Garmin Training Centre (locally on PC) in Garmin Connect and in Strava plus Runners World Runhub so I hopefully should be able to retain it indefinitely somewhere :)