"Unavailable network resource" message - please explain!

I keep getting the message:

“The feature you are trying to use is on a network resource that is unavailable.”

screenshot

I have deleted in program files and tried to reinstall a newer version but this keeps showing. Could someone please explain?

I started to use libreoffice which I had not used for a while and checked for an update. One was available so I downloaded it, I started to install it, it went so far then when it appeared to be trying to delete the old version this box came up. I downloaded an earlier version 5.4.6.2 this happened again. I went to program files in "c"drive and deleted libre office because when trying to delete it in programs and features a very similar alert happened. I have now no office and when itry the same thing happens

These are the messages I am getting when I try:

error_message

This message is from Windows Installer, and the wording is chosen because of the intended method of deployment of applications in corporate environments - administrators put .MSIs to network shares, then assign domain computers to install from there, and after that, the original source may become unavailable. The wording has nothing to do with the actual placement of install media neither at the moment of installation, nor at the current time.

See this answer for other parts of your question. Especially note that “deleting program files” is not equal to uninstalling a program: the history of it being installed, as well as the files in other locations (e.g. fonts), registry settings stay and interfere with following installations.