To address the issues you're experiencing while setting locations in Google Earth using latitude and longitude or postcodes, follow these detailed steps:

1. Check Internet Connection

Ensure that you have a stable internet connection, as Google Earth requires internet access to retrieve location data.

2. Update Google Earth

Make sure you have the latest version of Google Earth installed. An outdated version may cause issues with location settings. To update:

- Open Google Earth.
- Click on "Help" in the top menu.
- Select "Check for Updates" and follow the prompts to install any available updates.

3. Use Latitude and Longitude Correctly

When entering latitude and longitude:

- Ensure you're using the correct format. The format should be in decimal degrees, for example, "37.421999, -122.084057".
- Enter the coordinates directly into the search box at the top left of the Google Earth interface and click "Search".

4. Attempt Using Postcodes Differently

If using postcodes leads to failures:

- Try entering the postcode into the Google Search bar within Google Earth instead of the search input box. This may yield better results.
- If the postcode doesn’t work, ensure it's valid and corresponds to a recognized geographic area. You can verify on a dedicated postcode lookup website or tool.

5. Troubleshoot with Google Earth Repair Tool

If you continue facing issues:

- Open Google Earth.
- Navigate to "Help" and select "Launch Repair Tool".
- Follow the instructions to repair any issues within the application. This step may help fix corrupted files or cache issues - learn more.

6. Clear Cache

Sometimes, clearing the cache can resolve display issues:

- Go to "File" in the menu.
- Select "Clear Cache" under the "Options" section (note this might not appear in all versions).

7. Check Location Settings (if applicable)

Verify that location services are enabled for your device if you're using Google Earth on a mobile device. If you're on a desktop, ensure your operating system’s location settings are configured correctly.

8. Use Alternative Input Methods

If these methods do not yield results, consider using Google Maps to find your desired location first. Once located, you can use the latitude and longitude information provided in Google Maps to enter into Google Earth.

9. Seek Further Help

If you encounter persistent issues, consider searching through the Google Earth help forums or communities where you can find potential solutions or post specific queries - learn more.

By following these steps, you should be able to successfully set locations using latitude and longitude, as well as troubleshoot any issues with using postcodes in Google Earth.