Calendar error message

[TJB]

When I try to add an appointment to my calendar I get a message saying:
The form required to view this message cannot be displayed. Contact you
administrator.

I can't open any appointment forms. I downloaded Out look Add ins a day or
2 ago. Is this having anything to do with the problem. If so does anyone
know how to repair this.
Keep in mind you answers need to be precise & in clear language. I am not
a computer whiz.
Thanks in advance.

 

[Aligator]

since you're not a "pro" i'd suggest the easiest thing to do is to uninstall
outlook and reinstall it from scratch