The most common problem that you are running another program which is blocking port 80 or 443. If you have installed Skype, then you have found this problem.
1) Open Skype
2) Go to Tools
3) In Advanced settings click Connection option
4) Uncheck option – Use port 80 and 443 for additional incoming connections
5) Click on the Save button same as given image, see below:
6) Now Restart your system.