Question USB ports not working. New Builder

Apr 13, 2019
I have the ports plugged into the motherboard and have a keyboard plugged into the USB. Just pulled the desktop out of the closet and tried to get it working today pulling parts from another computer I took apart a while ago. Got the PC to turn on and got it to the Windows 10 login screen. But the bios says that there is a keyboard failure. I tried the ports sticking in a flash drive that lit up but only for a second and I can't boot off of that. Left the PC unplugged with the keyboard unplugged for over 3 hours. Tried looking online for a solution, tried many troubleshooting. Found this form recommenced for PC questions. I just don't know what I'm doing wrong. Like this is my first time assembling a PC and like I put all the USB cables in the corresponding colors. I wonder if the 12/2 pin thing on the motherboard that says "serial PS2" could help me like by putting a adapter on it for a mouse. Thanks in advanced!😊