my windows 10 system is broken

so i basically wanted to create a new user with the cmd command net user "name" /addi logged on that account then i wanted to go back to the other account but i could not find it in the start button of windows because i didn’t open it (it was broken or corrupted maybe) it i tried fixing with other commands but it turns out i didn’t have permissions on this account and i runned 20 different repairing tools but nothing now im here with this user with no permissions and i don’t know what to do anymore

(sfc /scannow does not work)
if i can fix the start menu maybe it will fix it