Emulator won't launch in android studio for hours

I know this question has already been asked, but I have gone through all the answers and cannot find a suitable solution.

whenever i run any app it shows Waiting for Device. C: \ Android \ sdk \ tools \ emulator.exe -avd Nexus5 -netspeed full -netdelay none and the emulator won't start for a few hours.

• when i click the launcher icon in avd manager nothing happens.

• I tried resizing the ram to 768MB as mentioned in the post ... and tried deleting old avds and creating new ones, but nothing seems to work.

• emulators worked well with ecllipse, but not in studio.

suggest something to understand. Thanks in advance.