Can't create documents

I have Libre Office installed by the installer for teh KDE Neon linux distribution. When I open Libre Office, the panel along the left side of the window has a “Create” header about half way down. Below that header are a list of document types. All are disabled. If I navigate the File->New menu, the only choice is Template. The templates dialog has no choices for spreadsheet. For document, it only has a couple of letters and a resume. How do you create a blank document or spreadsheet? I have three xlsx files created by Microsoft Excel and all of which open fine in Microsoft Excel. When I try to open them in Libre Office, it says 2 of the 3 are corrupted. On the third, it gives me a dialog for filters with only ‘chart’ choices. So, I can’t open existing documents or create new ones. Please help!