Ihave no mail list with my folders on the left tasks calendar and contacts.Before had a whole list with sub folders what am i doing wrong??

Ihave no mail list with all my folders on the left side only tasks calendar and contacts.Before i had a whole list with sub dolders and everything what am i doing wrong??

When this has happened to me, it’s because I’ve accidentally set the Mail widget not to display.

Go to the bar that says Calendar, and right-click. You should get a list of the various things that can be displayed on the left. Re-enable Mail.