Why doesn't the green checkbox appear in open server?

Question

Windows

Good afternoon. I installed open server on windows, installed it, didn’t show any errors, right-click on the red flag, start it, the flag turns yellow for half a minute and turns red again, I write localhost does not open in the browser.
Tell me what's the problem

Answer 1

Shut down Skype and restart the server. If there is no skype, see what port 80 occupies

Answer 2

It happened to me when I unsuccessfully played with the settings. So you can try to reset the settings to default. Or really see what's up with the ports. Maybe some applications like PostgreSQL, etc interfere.