3 possible solutions for you.

1. Make sure your laptop is plugged into the mains power not just running of its battery power. Try changing the order of turning on your devices. So for example if you usually turn on the TV and then the laptop try turning on the laptop first then the TV. Try switching to another input on your TV source button then back to Hdmi.

If that doesn't work


2. Turn on your Dell laptop and then power on your HDTV or LCD monitor. Navigate to the correct "Input" channel on your TV or monitor.

Hold the "Fn" key on your keyboard, then press the "F1" button to engage the video output. Your laptop's display should now appear on the TV or monitor.

If that doesn't work.

3. Press the “Start” button on your Windows Taskbar, and then select “Control Panel.” Click Hardware and Sound option, and then choose “Manage Audio Devices.”
Select the “Playback” tab. Click the HDMI device on the Playback tab and then press the “Default Device” button to make this your default audio device. Press “OK” to save the option.
Press the “Start” button and select the “Control Panel” again. Select “Power Options,” to set the power plan for your system. Select “High Performance” to keep the HDMI audio working when the system is not plugged into the electrical outlet.