I only have physical copies but if I lost a town over a year old, I'd panic, I'm not sure what causes this..it's why I never got a digital but I try to be extra careful even if someone is in a rush when switching carts to take my time, make sure I power off, change the town dates correctly this almost got me once save the fact I went back on accident on a day someone was denied moving got a ping and went back correctly. But to lose a town especially with most dreams and time is hard. I hear this happening more and more, and have done the accidental pop out before powering off but not while game was loading..I hope it never happens and to all who have had it am so sorry all you can do is try again. With physicals would like to know what caused for you. Ive been leaving my carts in the plastic cartridge boxes on my patio where I play it's been raining saw one was left out hope that didn't hurt it, that's my biggest worry moving them in it's been rainy.
I've been lucky enough to be over a year on one having dropped the machine to all kinda of things and never gotten this crosses fingers. My first town may not be played as much until lately again but I feel your pain, I can't imagine, I've never reset...just started a new separate so this does scare me as they are all distinct but linked, lose one my almost finished dream finishing falls.
If you need any start out stuff I'm sure people will try to help, who did you lose?