maybe your firewall is blocking this?

all fonts or just 1?

I can not download all Google fonts and I did not do any changes to Windows. 

Also, when I start my project I am receiving the message " Some fonts used in this document have not been linked to the project

MIRIAM FIXED

They will be replaced by the templete default font.

This project had no errors before.  When I checked font selection it looks like only one Incomedia WEB FRIENDLY font is listed from available fonts. Please advice.

Ad miriam fixed in any text object in the text options pulldown menu (way below)

Search for the font on internet, download it and add it (depends on what file you find on internet) in the tab WEB Font

see also: http://help.websitex5.com/en/v15/pro/web_fonts.htm?zoom_highlightsub=web%2Bfonts