Troubleshooting Steps:
1. If the icon is missing, clear the data and cache using this path: Settings > APP Management > APP List > System > Launcher > Storage usage, then restore the icon.
2. If the Theme Store is truly missing, check the path: Settings < APP Management < Recover Uninstalled System Apps (for realme UI 2.0 and above), and install it again.
3. Search for "Theme Store" in the Built-in App Market (for the Middle East Asia version Theme Store, users can install it from Google Play), then install it.