Desktop left on, turned off at some point, and won't turn on again

I built a Desktop computer a while back (about 2-3 years) and I left it on for some updates for steam and epicgames last night. Woke up this morning to find that it was off. tried to turn it back on and there was nothing. I checked the chord and it is getting power from that, I checked the back of the computer to make sure the power supply was on(it was ad I flipped it off then on again to make sure), I took a bit of it apart again and checked the power switch to check if it had continuity and when I pressed it, it was at 0 (like it should) and when I released it, it went to 224(I don't know too much about measuring continuity beyond 1 or OL means no connection and 0 means there is no resistance). I don't know if checking if the switch is getting any power means anything since it is hooked up to the motherboard and not the power supply, at least thats how I think it goes. Also there was no storm that knight (I heard that leaving a PC on when lighning could strike could potentially cause a problem)What could possible problems be and how could I fix them?