Have you tried to give your PC any sleeping pills? maybe PC has been under a lot of stress recently.
I know, I know. I'm not funny
seriously though. Try changing these settings in your Power Options.
If that doesn't work it might be some device or driver preventing your PC from shutting off when trying to go to sleep. Try disabling wifi, Ethernet, Bluetooth and anything else you can think off. It might also be your HDD is not allowing your PC to sleep. try...