reset password dell inspiron

HI  I recently down loaded windows 10  when I turn on my desktop, it wants my administrator password , which I haven,t had to use in years  I don't remember it. so when I try to reset it .it says there is no password reset disk. and says to install a usb flash drive. I purchased a flash disk . and now the computer says it,s not a password reset disk.   is there a special disk I should purchase, or is there an easier way to get my password  thank you