I restarted my MacBook and there were question marks in the place of text on the home screen, why did this happen and what does this mean? Should I be worried? -
![Mac displays a folder with question mark : Få Ødelagt Slettet Mac data tilbagebetalt - mac dataene inddrivelse Mac displays a folder with question mark : Få Ødelagt Slettet Mac data tilbagebetalt - mac dataene inddrivelse](http://imageshack.com/a/img924/9169/Z9aFx0.gif)
Mac displays a folder with question mark : Få Ødelagt Slettet Mac data tilbagebetalt - mac dataene inddrivelse
![MacBook Pro flashing question mark but I can't repair because hard disk not found in disk utility - Ask Different MacBook Pro flashing question mark but I can't repair because hard disk not found in disk utility - Ask Different](https://i.stack.imgur.com/G7wYF.jpg)