Re: [Guide] How to get the WampServer icon white instead of red or yellow!
The Yellow state means the one of the two services didn't start, either Apache or MySQL. You need to fix the problem that caused the service not to start. Check your log files, it will usually tell you why or what the problem was trying to start. Check also your windows event log, it might give you a clue as to what went wrong.
HTH, vbplusme