Try clearing the app's cache. I have an S3, not an S4, so how you get there might not be quite the same, but on the S3:
Go to Settings / Application manager. Scroll all the way right, to the "All" tab. Scroll down to "Google Play Store" and tap that row. Tap "Clear cache", then "Force Stop."
Now go back to the home screen, and restart the app. See if that fixes it. If not, try the same thing again, but this time "Clear data" instead of cache.
If that still doesn't work, go back to the Application manager, tap the menu button, and "Reset app preferences." You ca n also check at Samsung India site in its support option.