Resetting Password

I have an italian keyboard on my mac, and when I turned it on after shutting it down the day before, when I tried putting my password in, it told me it was wrong. In the top right corner, it said that the keyboard was italian, but I figured out that it was actually set as american. My theory is that since my password included the letter "ì", which is on the italian keyboard and not on the american keyboard, when I put the password in, it didn't recognize the letter. I tried resetting it using my apple ID, but when I got to the final step, it said you may now use your new password, but I didn't put any new password in, so when I tried putting the old password and my iCloud password, it didn't work. I also tried going to OS X utilities and using resetpassword with terminal, but I couldn't select a user. I would appreciate it if you could help me as soon as possible because I need my mac for a school presentation in three days. 😕