Since Office 2016 and Office 365 came about, the most recorded problem I have experienced has been with MS Outlook refusing to work. Hopefully, the following will help.
Outlook disappears when minimised

The following assumes Outlook is already open:
- Right-click Outlook in the System tray (see Image 1)
- Clear the Hide when minimised item
If you can’t find Outlook in the System tray:

- Right-click the Outlook shortcut you use to open Outlook
- Select Properties.
- Select the Shortcut tab
- At Run: make sure this is set to either Maximised or Normal Window ( and not minimized)
Removing Outlook Add-ins
However, if neither of the above fixes your issue, because you can’t actually open Outlook, or Outlook opens but then freezes or shuts quickly after, then the following should help:

- Restart your machine
- Open Outlook if it will let you.
- If it won’t let you then we need to open Outlook in Safe mode:
- Press Windows key + R key at the same time to open the Run command box
- In the Run command box, type Outlook.exe /safe and press OK

Now Outlook is open, we can fix the issue.
- When Outlook opens, click File > Options > Add-ins
- At the bottom of the View and Mnage Office Add ins section, make sure the Manage box shows Com Add-ins and click Go.

You would need to untick these Add-ins to get Outlook working
- Take a screen shot of what you have ticked, for future reference if needed.
- Untick all add ins and click OK.
- Click File > Exit.
- Now restart the computer and Outlook should start properly.
It is a good idea to check for new plug-ins every time you install new software, particularly if it is Microsoft. I know that MS Teams will install an add-in that will cause Outlook to stop working.
You can find out more about this problem in the Microsoft Support pages.