If what you bought is just a cable with a VGA connector on one end and an HDMI connector on the other end, it will never work for you.
You probably bought an HDMI to VGA cable. That won't work in reverse.
The VGA port on your computer produces an analog signal.
The HDMI port on your fancy new TV requires a digital signal.
You need an adapter that converts analog to digital. These converters need to be powered, which is why all VGA to HDMI adapters have a USB cable that connects to a USB port on your computer AND -- because HDMI carries both audio and video signals -- an audio cable that will connect to the audio output port on your computer.
You need something like this: https://www.amazon.com/FOINNEX-Converter-Computer-Projector-Portable/dp/B07121Y1Z3