Click on Start, Run, and type services.msc.
Locate your Windows Firewall and make sure the service is on Automatic and Started.
Or,
Click on Start, Run, type msconfig.
Under the Services tab, put a check mark on "Windows Firewall".
Or,
Click Start, then Run and type CMD in the dialogue box that appears, and then click OK. Type netsh winsock reset into the DOS window that appears.
If still no luck,
Click Start, then Run and type CMD in the dialogue box that appears, and then click OK. Type netsh firewall set opmode enable into the DOS window that appears.