Hi. This will largely depend on the device model you have but the steps below outlines the cause you are to essentially take.
Download the APK here http://www.apkmirror.com/apk/google-inc/google-play-store/google-play-store-5-2-13-android-apk-download/ and install it as per the tutorial here http://www.satechhelp.co.za/2256/Install-Apk-Android
Download the APK here http://www.apkmirror.com/apk/google-inc/google-play-store/google-play-store-5-2-13-android-apk-download/ and install it as per the tutorial here http://www.satechhelp.co.za/2256/Install-Apk-Android