Hi Michel_864,
· Do you remember making any changes off late?
· Have you tried booting in safe mode?
Check to see if the following helps.
**Method 1:**Disconnect any non-essential devices connected to the computer and restart. Check to see if it boots normally.
**Method 2:**You may need to check the BIOS (Basic Input\Output System) settings. Check to see if the hard drive is detected. If not, check for the physical connections. Refer to the manual to check for the same.
Note: Be careful when changing BIOS settings. The BIOS interface is designed for advanced users, and it's possible to change a setting that could prevent your computer from starting correctly.