Font-Preview ... some fonts no sample, just squares

1. Your screenshot shows not the Details view. But this doesn't help much because some of the Windows fonts are not created by Microsoft.

Example:

2. Windows Fonts:

All Windows Fonts since 3.1

https://en.wikipedia.org/wiki/List_of_typefaces_included_with_Microsoft_Windows

You may not have all of them, but these are originals supplied with Windows. Possibly some are discontinued.

3. MS-Office:

Office 2016: https://social.technet.microsoft.com/Forums/office/en-US/aeb08f61-5b68-4a90-a83c-ea5163b3c978/where-is-a-list-of-fonts-that-are-included-with-office-2016?forum=Office2016ITPro

Office 2013: https://support.microsoft.com/en-us/help/2800393/fonts-that-are-installed-with-microsoft-office-2013-products

Office 2010: https://www.microsoft.com/typography/fonts/product.aspx?PID=163

3. Adobe fonts:

Creative Cloud: Adobe delivers a very basic set only:

C:\Program Files\Adobe\Adobe InDesign CC 2017\Resources\Required\Fonts

They do not appear in C:\Windows\Fonts.

4. What I see on your screenshot:

All fonts with names in Capitals (ABIGAIL, ABRACADABRA, ACTION, ADONIS ...) and all fonts with EF in their names are NOT Windows / MS-Office / Adobe.

These fonts came as single installations or with another program on your PC. Delete them or not. They do no harm. I would copy them on a USB stick or another secure place and delete.

5. If in doubt sometimes it helps to do a right click on the font file > Properties > Details.

6. As I said before: The fonts with the squares aren't harmful for your OS or apps or home printer. I just would not give them to a print shop with my design because they are of poor quality and could make problems there.

Fenja