I did all this bt then lappi got restarted and now question mark sign is coming and nothing is happening

[teja.aman]

After restart process the lappi got restarted and now question mark blinking sign is coming and nothing is happening. What to do.

 

[velocityg4]

Boot into recovery mode. Then you can try reinstalling macOS. If the computer worked fine before. Your hard drive or SSD may have failed.

https://support.apple.com/en-us/HT204904