First test all the physical connections. Make sure the video cable (HDMI, DisplayPort, VGA, and DVI) both ends are well fitted in the right ports on the monitor and the computer. Ensure that the power cable of the monitor is firmly fitted at an active socket and the device as well. A typical reason is the loose connections.
Select the right input on the screen. Cycle the input sources (e.g. HDMI 1, HDMI 2, DisplayPort) using its physical buttons or its OSD menu. Make sure the type of input you choose goes with the cable attached to your computer. Sometimes manual selection is required.
Make sure the graphics output of the computer is correct. By using an integrated GPU, plug the cable directly into the dedicated GPU, without going through the motherboard port. Shut down the computer and turn it on again. With desktops, shut down, press firmly (with sufficient force) to seat the graphics card into its PCIe socket and then boot again.
Critique the bad hardware. Make sure that the monitor is operating the other known-to-be-working computer. Make a test of your computer with a different, already-tested monitor. Swap the existing video cable with a known-good spare in order to rule it out as the failure cause.
Use more profound system re-sets. The monitor should be restarted to factory settings in its OSD menu. Do a complete computer reboot, shut it down completely, pull the plug, wait 30 seconds, and plug it back in again and restart. Ensure that the dedicated GPU is powered well and the fans are working.
Conclusion:
To fix the no signal issues, the issue should be solved based on proper troubleshooting. The first thing one should check is cable integrity, locked connections, and proper input choice. Advance to the stage of testing parts of the device separately in order to pin down the fault. It is mainly through mere negligence that most of the issues arise. System failures are persistent which is an indication of possible hardware requirements.
