AVD doesn't work after installing Android Studio I installed Android Studio, but when I try to run, the emulator is not working. When I googled, I find some instructions in which the 


  
  Open SDK Manager and Download Intel x86 Emulator Accelerator (HAXM installer) if you haven't.
  Now go to your SDK directory (C:\users\username\AppData\Local\Android\sdk, generally). In this directory Go to extra > intel > Hardware_Accelerated_Execution_Manager and run the file named "intelhaxm-android.exe".
  
  In case you get an error like "Intel virtualization technology (vt,vt-x) is not enabled". Go to your BIOS settings and enable Hardware Virtualization.
  Restart Android Studio and then try to start the AVD again.
  


but I don't know where is BIOS setting of my computer. I have HP desktop CPU and try to find the BIOS from start, F10 as well as from change PC setting in Windows, but all in vain.
I faced a similar problem recently on my windows 10 laptop and found out that the Intel virtualization technology (vt-x) was disabled from BIOS.

In case you are using a new laptop which comes per-installed with Windows 8/8.1/10 then chances are that you cannot enter the BIOS manually while booting. Reason being they have changed BIOS to UEFI which is no longer accessible through boot but instead you need to do the following steps:

Go to Windows > Settings > Update and Security > Recovery.
Then under Advanced startup, click Restart now. The system will restart and show the Windows 10 boot menu.
Select Troubleshoot > Advanced options > UEFI Firmware Settings.
Click Restart to restart the system and enter UEFI (BIOS).
from here you can access the UEFI menu (which is similar to BIOS)

Search for the VT-x setting (It may be named as Intel VT or Vanderpool or Virtualization Extensions or something similar depending on your OEM and BIOS.)

Please refer to this link for screenshots on how to access the UEFI from windows 10: http://www.howtogeek.com/213795/how-to-enable-intel-vt-x-in-your-computers-bios-or-uefi-firmware/