Using Win 10 64 bit on Dell tower computer
downloaded 7.0 and it won’t open.
Did you install or doesn’t even the installer open?
If installed - does it open in Safe Mode?
If you are having a problem with installing LibreOffice on Windows, look at General Installation Issues (Windows).
You could also look to see if Windows has blocked installation of programs originating outside the Microsoft App Store. In Windows click Start menu > 
Settings > Apps > Apps & Features and check that under the top heading Choose where to get apps make sure the field is set to Anywhere. A version upgrade might have set to MS Store Only. Cheers, Al