I am using XAMPPS to host PHP files from my machine. I have recently installed XAMPPs but I am unable to start Apache service as port 80 is in use by PID 4 - NT Kernel &
It means port 80 is already used by another one.
Simply follow these steps:
OR
For find the port of Apache (80) in Command Prompt simply type netstat -aon it displays present used ports on windows, under Local Address column it shown as 0.0.0.0:80. If it displays this port another connection is already used this port number.
Active Connections in Windows XP:

I solved my problem after installing xampp-win32-1.6.5-installer previously I used xampp version xampp-win32-1.8.2-0-VC9-installer at that time I got this error. Now it resolved my problem.