Libre Office Calc locked

Linux Mint 19. fullscreenonly I recently uninstalled Libre Office Writer and Calc. because I was having problems loading some of my documents, I then rebooted and reinstalled both via the software manager.
Now, when I open a Spreadsheet file, the page opens on full screen, with the only option at top right, to close the window, If I click on the solitary X (top right), a window opens showing all my Calc files instead of closing. I cannot reduce screen, also when I select Print Preview, the full screen opens showing No Data. and I cannot print,
Also when I try to close the file I find the screen frozen, the cursor will not activate anything until I tap the Esc key
I have also just found out that if I attempt to look at LibreOffice - Help - to see what version I have, nothing happens, it wont open. nor will anything under Help, Donations takes me to an unavailable site.
Any suggestions please

Ubuntu - and therefore Linux Mint - recently faced massive problems regarding their LibreOffice packaging. What does sudo apt list --installed | grep libreoffice tell? sudo apt check throwing any error messages?

Hello and thank you for a very prompt reply.
sudo apt list --installed | grep libreoffice gives me:-

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

libreoffice/bionic,now 1:6.4.2-0ubuntu0.18.04.3 amd64 [installed]
libreoffice-base/bionic,now 1:6.4.2-0ubuntu0.18.04.3 amd64 [installed,automatic]
libreoffice-base-core/bionic,now 1:6.4.2-0ubuntu0.18.04.3 amd64 [installed,automatic]
libreoffice-base-drivers/bionic,now 1:6.4.2-0ubuntu0.18.04.3 amd64 [installed,automatic]
libreoffice-calc/bionic,now 1:6.4.2-0ubuntu0.18.04.3 amd64 [installed,automatic]
libreoffice-common/bionic,bionic,now 1:6.4.2-0ubuntu0.18.04.3 all [installed,automatic]
libreoffice-core/bionic,now 1:6.4.2-0ubuntu0.18.04.3 amd64 [installed,automatic]
libreoffice-draw/bionic,now 1:6.4.2-0ubuntu0.18.04.3 amd64 [installed,automatic]
libreoffice-impress/bionic,now 1:6.4.2-0ubuntu0.18.04.3 amd64 [installed,automatic]
libreoffice-math/bionic,now 1:6.4.2-0ubuntu0.18.04.3 amd64 [installed,automatic]
libreoffice-report-builder-bin/bionic,now 1:6.4.2-0ubuntu0.18.04.3 amd64 [installed,automatic]
libreoffice-style-colibre/bionic,bionic,now 1:6.4.2-0ubuntu0.18.04.3 all [installed,automatic]
libreoffice-style-tango/bionic,bionic,now 1:6.4.2-0ubuntu0.18.04.3 all [installed,automatic]
libreoffice-writer/bionic,now 1:6.4.2-0ubuntu0.18.04.3 amd64 [installed,automatic]

and

sudo apt check

[sudo] password for pete:
Reading package lists… Done
Building dependency tree
Reading state information… Done
pete@pete-Aspire-TC-280:~$

Thank you, I hope this helps