If you do not have the VirtueMart component installed, please follow these steps to install it to your joomla:
Download the latest stable version here.
Unzip the downloaded file com_virtuemart.2.x.y.extract_first.zip - this will extract two more zip-files:
com_virtuemart.2.x.y.zip - which contains the main VirtueMart component.
com_virtuemart.2.x.y_ext_aio.zip - which contains all modules and plugins essential for VirtueMart.
Log in to your Joomla Admin Panel and go to the Extensions Manager.
First, install the com_virtuemart.2.x.y.zip extension.
Second, install com_virtuemart.2.x.y_ext_aio.zip extension.