If the BIOS screen shows then there is hope. But if not, then a lot more details are needed. That will not fix a card/system that won't display on VGA but you left out the details.
I just relocated my monitor that had a DVI to another computer and attached a VGA monitor to the computer. It worked fine. Now I have re-started the computer and the monitor goes into sleep mode and is not responding.
Should I have reset graphics before re-start? Monitor was working so I didn't worry about it.
What to do now? I don't have old DVI monitor available.