The below error appears when the previous process of the emulator is not closed properly in the system:

No emulators are currently running. To launch an emulator, use the Device Manager or run your app while targeting a virtual device.

To solve the problem, one has to kill the below process manually from the Windows Task Manager:

qemu-system-x86_64.exe

Once the process is killed then restart the emulator in Android Studio. It will work.