Hello pr3datorgaming126
Can you please confirm what you meant when you mentioned 'Can't Sign In'? Is Windows able to boot and you aren't able to use your username/password to sing in, or the PC isn't able to detect the hard drive itself?
Usually, the type of error you are seeing occurs when the computer fails to detect any boot files to load in the memory. If that is the case, you can check the BIOS configuration and see if the HDD is set as first boot device.
You can also check if any USB drive is connected to the computer that is keeping it from booting.
Please report back with the details to allow us to help you with a better, more accurate solution.
Cheers!!