I get to the last steps of help but it won't allow my phone to restore without telling me what the unknown error is. what should I do?

my iPhone 11 Pro just went black and stopped working. after a while it was just flashing the apple sign which then I pressed my volume button an on button which sent me to restore iPhone which instructed me to plug my phone in to my laptop. I did that which then opened up a restore and update iPhone. I try to restore and update but it doesn't work and tells me that there is an unknown error. im now stuck on what to do next