Mind sharing a picture of your system, a picture of the connector and the place you've found it disconnected in your system? If it's an 4pin or 8pin EPS, it should be located around the CPU socket. If it's a PCIe connector, it should go into your PCIe graphics card's power connector. Seeing how you don't know which is what, I'd suggest you also list your specs like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS: