Blender uses True Type and Postscript Type 1 fonts (if memory serves)

You can set the default font path in User Preferences

In User preferences i have set to Windows/Fonts folder.
Blender see only default fonts.
All font blender dont see is ttf format.

Got an example for us of a font file that doesn't work?
Please attach it.

1 - Folder - Windows/Fonts in Directory Opus on Windows 10

2 - Windows/Folders in Blender (after Shift+a - text)

Check the font-type (file extension) which Blender does not see.
Try turning off the file-type filter (at the top right).
Try uploading a file from another directory, not Windows/Fonts.

It may also be that the fonts you see in Windows Explorer (Fonts folder) are actually in a different folder! Check it.

When i select a different font directory (no windows/fonts) Blender see all the fonts, both TTF and OTF format. And loads them without a problem.
When i right click on a font (which the blender can not see in the windows/Fonts directory) and click install (or install for all users) font appears in windows/fonts directory but blender do not see him. But in different directory he sees without a problem.
All installed fonts are in Windows/Fonts directory.

Personally, if the blender sees all the fonts in a different directory, this is not a problem for me.

I think when you install the font, it is not real copied to the Windows/Fonts directory, it is only "linked".

Other programs see those fonts without problem.

After run this command:

Volume in drive C is System
Volume Serial Number is CCB6-9196
File Not Found

Do they show up (the missing fonts) if you simply do dir C:\Windows\Fonts\ ?

Yes they show up (default fonts). But without those missing by blender fonts. So You are right fonts are linked and not actually in that directory.

@Brecht Van Lommel (brecht) I'm guessing this is not something we plan to support for the 2.8 release?

What the progress of solving this bag? I have the same problem with the newly installed font. We need to resurrect this topic.

Blender never shines on the FONT side. The interface is waiting for improvement. Why we just can't select the font in drop filter like in other software? And have variations for BOLD, Italian version just through icons(or drop menu)?!!!

We do not have any developers to allocate to this in the foreseeable future.

Note that this doesn't mean that we will not accept patches that improves font handling ;)

When I install a new font on Windows 10 (build 19033.1) it usually goes to:

C:\Users\<username>\AppData\Local\Microsoft\Windows\Fonts

So its not Blender, it is Windows we need to blame..

For references, this is explained in this answer on Blender's StackExchange.

Literally just create a folder on your desktop, plop a copy of (or the original) .ttf/.otf file into it, and then navigate to that via the blender font selector. Worked 100% for me, should work easily for the rest of you.