My mac keeps on spinning the wheel at startup

Whenever i reboot my mac, it has an apple logo and a spinning wheel. I usally can fix this by restoring my computer using my Time Machine drive, but i need another way because my latest backup is 4 days ago. I did some pretty important things then, and i dont want to do them again.

Things ive tried:

• Booting in safe mode (didnt work...)
• Plugging my mac in and out (didnt work...)
• Repairing my disk. (didnt find any problems to fix...)

Also, is there a way to stop it happening again?