folders and inbox have dissapeared

After the last upgrade The programme was useless. I have since done a system restore to a previous date now I cannot access my inbox and ALL my folders with ALL my info has disappeared I am very disappointed as before the “upgrade” everything was fine.
here is all I get on my screen! HELP

Hello Eric,

It seems like Mail tab is just hidden, try to viewing it by right click on Calendar and tick Mail if it’s not ticked.
In case this won’t help, please let me know.