I have been experiencing WAMP Server issue which is yellow sometimes, thus I find out why is this happening and I found 2 solutions straight away to deal with this.
What do you need to know first is: #1 - Check what application is using port 80.
How? #1 – Left click on your WAMP Server icon in your task bar and hover your mouse to Apache > Service > Test port 80. Wait for less than one minute then a window pop-up will appear and shows the result of what application is using the port 80.
What to do next is: #2 – Go to you Administrative Control > Services. Look for Web Deployment Agent Service (MsDepSvc) then double click on it and stop the service! Next, click your WAMP Server icon again and Restart All Services. You will see the icon is green by now.