Local or network calendar? If network, who's the calendar provider?

Also, please explain in detail

• what you're doing,
• what happens, and
• what you expect to happen.

Local calendar on my laptop. I am just using Thunderbird normally, as a email client and using the calendar mode to keep track of my important dates. Nothing special in my use of this software. Remember it worked fine before the latest Thunderbird update. I can't add new important dates on the calendar, nor edit old date entries. If I copy a previous entry to use on a future date, the drop down menu by right clicking the mouse does NOT show a paste entry. In summary, I cannot edit old calendar entries, I cannot add new entries, I cannot copy and then paste new entries, etc. In other words, the calendar function does not work. It does display my previous entries but I cannot make ANY CHANGES OR ADDITIONS. Remember, the Calendar Function worked fine on the PREVIOUS version. The new update KILLED the calendar function.

Make sure the calendar isn't read-only. In the left pane of the Calendar tab right-click the troubled calendar - Properties. Is the 'Read Only' box un-checked?