Mac book air

My Mac book air has recently been freezing for periods on time but still playing my YouTube in the back ground I can’t seem to do anything but just close my lap top

but today was different I was watching YouTube when suppendly it stopped and went to a black screen but I could here the sound behind it so I closed my Mac and put it on charge and I went to re open it and the fans turned on and started going fast and getting loud and the screen would come back but it came back to the YouTube video I watched before the swap to the one I was watching when my Mac froze and then nothing happens I can’t move it or anything

I need help ASAP all my school work is on here