Android 4.1.2 is an older version of the operating system, and the built-in Play Store app may stop working or fail to update automatically. Manually sideloading the APK can:

Versions around v25.x.x are typically the final stable builds for Android 4.1.2.

if it was accidentally disabled or uninstalled. Essential Requirements for Android 4.1.2

to the final version that supports Jelly Bean.

Navigate to a trusted repository to find the compatible file:

Search for Google Play Store (Android 4.1+) and select a version like 25.2.27 .