I did not know there is a difference btw Web-IDE and Web store IDE. In fact I use Web Store IDE. In the past it worked fine with the same PC and Win7, but something went wrong and I can not connect any more. I will provide later some screenshoots with the "status".
Are there any way that some antivirus or corporate security system can block access to the com port? There were some updates on PC to porvide more security
I think @parasquid is spot on here. It's a bit confusing but there are some a few different ways to run the Web IDE.
https://www.espruino.com/ide/ is the easiest but it needs an up to date chrome version for the Web Serial to work, and may require 'Web Serial' to be enabled via chrome://flags. If you're using this one then when you try and connect you should see a link called
Status, and clicking that should tell you why certain things (eg Web Serial) aren't working.
The Chrome Web Store IDE should 'just work' though: http://www.espruino.com/Web+IDE#from-the-chrome-web-store