I have a flashing file folder with a? When I turn on my computer what is wrong with it

If your Mac starts up to a question mark

A folder with a flashing question mark means that your startup disk is no longer available or doesn't contain a working Mac operating system.

1. Press and hold the power button on your Mac for up to 10 seconds, until your Mac turns off.
2. Turn on your Mac and immediately press and hold Command (⌘) and R to start up from macOS Recovery.
3. While in macOS Recovery, use Disk Utility to repair your startup disk.
4. If Disk Utility found no errors or repaired all errors, take either of these actions:

• • Reinstall macOS
  • Restore from a Time Machine backup

If you still need help, please contact Apple Support.