iMac stuck on start up Screen

My iMac is stuck on startup screen. Not moving forward. I tried all the 6 start up steps like turn on the power holding the option key, CMD +R key PVRM/RAM set up, etc.....

Nothing Seems to work at all. It's just stuck with the display of the Apple Logo showing half bar line. I have been doing this now for 3 days and it does not move forward.

Need help...