If you're unable to start your Mac in Safe Boot mode, or your Mac starts in Safe Boot mode, but it won't start up normally, you can try the following:
If it not helps, perform an Apple Hardware Test (AHT) which contains a suite of diagnostics that will test the hardware of your computer.
If it not helps, try to Repair Disk Permission. You need to use Disk Utility to Repair Disk and the Repair Disk Permissions. Check this tutorial to see how to use disk utility for these functions.
Hello i performed the steps you sugest me, and in the AHT i found an error the error is the following,
I think the problem it will be on the Hard Drive?
If you cannot boot into your system, you should connect your system with another mac machine with a firewire cable to perform a targetmode boot. Click here to see how to use and troubleshoot FireWire target disk mode
If your system do not have a firewire port, you need to take the disk from the system and then you can connect the drive to a sata-to-USB adapter or put it in a hard disk enclosure then connect it to another Mac system. From there, depending on the level of corruption you should be able to copy data from the disk or can repair the disk with third party tools.
With sata-to-USB adapter you can connect the disk to another Mac system like an external hard disk and can repair or backup its data. Click here to buy sata-to-USB adapter from Amazon