– Did the desktop sound and look like it was on? (There are usually some lights on it, the power button glows, or you can hear it turn on.)
– Did you shut down Windows, power off the PC, and was the monitor powered off BEFORE you began unplugging things? (not mentioned)
– When things were reconnected, did your cycle through ALL of the HDMI ports (with the TV remote)? (HDMI-1, HDMI-2, etc.)
– Have you tried connecting your desktop to your plain monitor using a non-HDMI cable, yet?
– If you connect your TV via HDMI to a DVD player or game system does it work?
It’s possible that you moved the video/graphics card while unplugging and moving the computer. Are you savvy enough to open the cover and reseat the components? (RAM, all cards, etc.) If not, track down a savvy family member, friend, or hire an IT tech to come out and test for you.