I forgot to add the following alternatives. Thank you.

1) How are you? I'm well.
I'm going to the mountains in Aosta Valley (to Aosta Vally- a region in Italy).
2) I destroyed/crashed/smashed/broke down/bumped the car.
Are the above verbs possible with CAR?
3) Can you suggest to me a verb which replaces: I had a smash up. (using a car?)
4)he entered her office.
5) It was three days since I met him for the last time (is it possible as a substite for "last"?)
The teacher had written a reprimand to her. (or written her a reprimand)
6) He left her (is it possible with the meaning of ""he dumped her?)

1. OK

2. Not "broke down" -- and not "bumped" unless you mean you bumped into another car with yours.

3. I was in a car accident. I had a car accident.

5. It had been three days since I last saw him.

The teacher had written a reprimand about her unacceptable actions in the classroom.
(not "written her" or "to her" because the reprimand was not a positive thing!

6. He left her <~~That words best if you're referring to people who are married. It could work for others, too, if they had been in a long-term relationship. Use these for boyfriend/girlfriend break-ups:
dumped her
broke up with her
ditched her