If you lose your mind, it means that you go crazy (volverse loco).
Other expressions with mind include:
To give someone a piece of one’s mind = regañar
The teacher gave the students a piece of his mind for arriving late for the exam.
The last thing on one’s mind = Lo que menos preocupa
I was so busy before Christmas that the last thing on my mind was buying presents.
Cross one’s mind = pasársele por la cabeza
It never crossed his mind that he had upset the boss when he told the joke.
Slip one’s mind = olvidarse
It completely slipped her mind that she had a dental appointment.
Have a one-track mind = ir a piñón fijo
He has a one-track mind, he’s only interested in body-building and spends every evening at the gym.
Be open-minded = tener la mente abierta
When I was a teenager, I nearly always did what I wanted as my parents were very open-minded.