How can I save my pc?

I was optimizing my pc, starting with limiting my cpu temperature to 80°C because it would run at 95°C idle. I was in BIOS settings, and I was watching a YouTube video on the cpu voltage. His BIOS menu was different than mine, but I thought it would be the same nonetheless. Boy was I wrong. The tutorial said to change cpu voltage from 1.5V to 1.35V. I went to go change it and it was at 0. I went from 0 to 1. After I restarted the pc to apply the changes, my monitor didn’t auto turn on. My HDD light stays off despite the pc being on, and none of the usb ports work. How do I change it back to normal? Is it unsaveable?