Suddenly Outlook not sending messages; cannot set up new account

My Outlook for Mac 

Version 16.105.3 has stopped sending messages. I tried re entering account info; port numbers, password, I deleted the account and re started my mac but with every task the "Add Account' button remained greyed (or blued) out. I could not press the Add Account button. iIhave downloaded a new Outlook from my 365 account but still no response. Also, all these steps now show all my mail folders and mail now gone; if I get the account back up and running will all my mail re-populate. I am anticipating all my rules will be gone. Thank you