My hackintosh won't boot and shuts down

I successfully installed and dual booted Windows 10 and macOS Sierra on my pc and everything was running smoothly and fine, but recently, every time i boot into macOS, the progress bar takes a really long time and then the pc shuts down before it could finish. It's really important that I get it to work because I have some really important files on it. Please help :/

Specs:

Intel Core i7-8 core 3770K Nvidia GeForce GTX 960 OC Gigabyte GA-P75-D3 8GB DDR3 RAM