Flashing folder with question mark

That indicates the computer cannot find a valid operating system. That can be:

• a faulty hard drive
• a physically missing hard drive
• an invalid operating system
• a corrupted operating system
• the computer has "lost track" of where its startup volume is located.

Please tell us what Mac this is and its sub-model. "Windows" in your equipmen line gives us no clues. The more info you can provide, the faster we can reach some form of resolution. We are your fellow end usrs and can neither see nor touch your computer so can only rely o yor for important details.

As the computer wil not properly start, if you do not remember the Mac sub-model, you can retrieve it by entering the serial number into this Apple Support page:

Check Your Service and Support Coverage - Apple Support

I would first see if the computer boots in Safe Mode:

How to use safe mode on your Mac - Apple Support

If that does not start it, next try booting to the Startup Manager using the SECOND bullet point in this article:

Mac startup key combinations - Apple Support

See if a bootable volume shows.

If that fails, you can try Recovery. Be sure the computer is connected to the internet first.

About macOS Recovery on Intel-based Mac computers - Apple Support

Gottie313 wrote:

How to fix a flashing folder with question mark on load up

If your Mac starts up to a question mark

https://support.apple.com/en-us/HT204323