android virtual device does not launch the emulator and gives error in android studio

Issue

i am new to android development i have installed android studio 1.01. sdk and avd managers work fine but when i want to launch my virtual device it gave me this error:

C:\Users\-----\AppData\Local\Android\sdk\tools\emulator.exe -netdelay none -netspeed full -avd Nexus_5_API_21

NAND: could not read file C:\Users\------\AppData\Local\Android\sdk/system-images\android-    21\google_apis\x86\/system.img, Invalid argument

i already searched both stackoverflow but didn't find any thing related :(

Solution

open sdk manager and make sure under API 21 system images are installed.

Answered By - PPD