tried to update to monterey and now my imac wont let me restart it

Hi! I tried to update my imac to monterey, everything went okay, it downloaded it and installed it and then when it was supposed to restart itself it just froze on my desktop picture. Only the picture is visible, no icons, not the bar at the top of the screen, just the picture. I waited for a bit to see if it was just taking a long time and then ended up force shutting it down. It turned on like normal but still has the big sur system as if i didn’t update it and now every time i try to restart it, it just freezes on my desktop pic and i end up having to force shut it down all over again which i hate :( Can anyone help me?

Thanks so much!