This is how to check if an app is disabled and reenable it.
1. Open SETTINGS.
2. Tap on APPS. You might see APPLICATION MANAGER. If you see it, tap it too.
3. You should see a list of your apps.
4. Under the APPS or APPLICATION MANAGER label at the top left of the screen, you'll see a menu button next to ALL APPS. Tap on the button and select DISABLED. That will show all the disabled apps on your device.
5. If your weather app is disabled, it should be on the list. Tap on it.
6. The ENABLE button should be available. Tap on it to reenable the app.