To troubleshoot a Dell WD15 dock, try the following steps:

1. Check the connections between the dock and the computer. Make sure that all cables are securely plugged in and that there are no loose connections. With everything plugged in, bend the cable to test the stability of the connection.
2. Check the power supply for the dock. If the dock is not receiving power, it will not be able to connect to the computer. There are power indicators on both the power adapter and the dock. If you received a 130W adapter with your dock, check if your laptop requires the 180W version. 
3. Restart the computer and the dock. This can sometimes resolve connection issues.
4. Update the drivers for the dock. If the drivers are outdated or corrupted, they may be causing the dock to malfunction.
5. (For display issues) Check the display settings on the computer. Make sure that the dock is enabled in the system's settings and that it is set as the primary display.
6. If the dock still will not connect, try using a different cable or port on the dock/computer.
7. If none of the above steps resolve the issue, please contact us for further assistance.