Chances are if your save reset for "no reason" you either cleared your cookies or your cache. if you want to keep it safe, find the file in your internet storage and copy it to somewhere. Google for better instructions.
I had 273 years left... also, I know this has been said before, but the clogging of the volcano would hurt more than help. Although I really enjoyed the way it illustrates that a small change can have a big impact down the line.
 "Idle Mine"){kind=icon}
 "400 Years"){kind=icon}
 "The Idle RPG 2:Renicipation"){kind=icon}
 "Flight"){kind=icon}
 "Burrito Bison Revenge"){kind=icon}