How to restore history and totals

Garmin 840 keeps on crashing and rebooting every 2/3 minutes when navigating menues in a situation where no activity is launched. (Noting that this behaviour does not happen during an activity). 

I would like to do a factory reset to see if this can resolve the issue. Can you tell me how to:

- restore all activity history

- restore « totals » 

after a reset

thanks!