Windows SmartScreen prevented an unrecognized app from starting. Running this app might put your PC at risk.

solution:-

Disable SmartScreen Filter in Windows 

1. Open Control Panel and click on Action Center icon. Alternatively you can open it by typingAction Center at Start Screen and it'll show it in Settings section of search results page.

2. Now click on "Change Windows SmartScreen settings" link given in left sidebar.

3. It'll open SmartScreen settings window. Now you can select "Don't do anything (turn off Windows SmartScreen)" option and click on OK button.

4. That's it. It'll immediately turn off SmartScreen feature and you'll no longer get the warning message in Windows 8.

BONUS TIP:

You can also change SmartScreen filter settings using Registry Editor. Just follow these simple steps:

1. Type regedit in RUN or Start search box and press Enter. It'll open Registry Editor.

2. Now go to following key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer

3. In right-side pane, you'll find a string SmartScreenEnabled. Just change its value to any of following:

• RequireAdmin (To require approval from an administrator before running downloaded unknown software)
• Prompt (To give user a warning before running downloaded unknown software)
• Off (To turn off SmartScreen)