Forceful Measures:

• Hold the power button: Press and hold for 5-10 seconds until it shuts down. This is a last resort, but sometimes a hard reset works wonders.
• Disconnect the power: Unplug entirely for a few minutes. This clears temporary power issues.

Software Sleuthing:

• Close rogue apps: Make sure no programs are preventing shutdown. Check running processes and close any you don't recognize.
• Disable Fast Startup (Windows): This feature can cause shutdown hiccups. Try disabling it in Power Options.
• Run system scans: Use built-in tools like SFC (/sfc /scan now) and DISM (/DISM /Online /Cleanup-Image /RestoreHealth) to check and repair system files.

Advanced Solutions:

• Boot in Safe Mode: This isolates essential drivers and services. If it shuts down normally, a conflicting program is likely the culprit.
• System Restore: Roll back your system to a time before the shutdown issue started. (Only use if you remember the date!)
• Hardware Check: If all else fails, consider hardware issues like faulty power buttons or overheating. Seek professional help for further diagnosis.

Remember, these are just starting points. The specific solution depends on your operating system and the nature of the problem. Don't hesitate to search online for your specific situation or seek help from tech communities or professionals.