What version of Godot are you using?
What OS are you using? (Windows, Linux, MacOS)
You can try to start the engine from a command line (e.g. cmd, powershell or bash) then you should see the error in the console window.
On windows this would be done like this:
1. open powershell
2. navigate to the folder where godot is: cd .\path\to\godot
for steam the path should be C:\Program Files (x86)\Steam\steamapps\common\Godot Engine
3. run godot by typing: godot.exe (or steam: godot.windows.opt.tools.64.exe)
4. you should now see the error in the console window