Log in under the account "Administrator". Open "control Panel" via "start" button. In the category "Network and Internet connection" click the "Windows Firewall" or select the task "Change Windows firewall settings".
In the opened window go to the General tab and set the marker in the "on (recommended)". In this group, you have the option "don't allow exceptions". When the field is checked, the firewall blocks all unauthorized connection request to the computer, including any service contained in the tab "Exceptions", as well as requests for access to shared printers and network devices. After you activate the firewall and configure the additional settings, click on the OK button, the dialog box will close automatically.
Sometimes it happens that the operating system could not start the firewall service. This happens in cases when file is corrupted SharedAccess.reg. To resolve this problem, you can go in several ways.
Call Setup API InstallHinfSection. To do this, click "start" and select from the menu "Run". In the empty field of the window that opens, type without unnecessary printed characters in cmd and click OK or press Enter. In the new window enter the command Rundll32 setupapi,InstallHinfSection Ndi-Steelhead 132% windir%inf
etrass.inf, press Enter, and restart your computer.
After rebooting again, invoke the "Run" window and rerun the command cmd. At the command prompt type Netsh firewall reset and confirm the command by pressing Enter. Call the "Run" window and enter the command firewall.cpl. After that, turn on the Windows firewall as described in the first two steps.
The other way requires editing entries in the registry editor. To make changes to the registry should be very carefully if you are not sure you can handle it, better to just reinstall the operating system. Usually helps to reinstall with a complete format the hard disk. Installation over the existing system sometimes does not bring the desired result.