Probably was "¿Tu has cambiado de idea? This refers to, if you have changed your point of view of something. So, probably in english you say: Have you changed your point of view? Are you sure?...

The literal translation of "Have you changed your mind?" is "¿Has cambiado tu mente?", but that in spanish sounds awkward and the real meaning is that you changed what you think about a particular topic. That in spanish is expressed as "¿Has cambiado de idea?" which if you make the literal translation would be "Have you changed of idea?". In short, you translate (or should I say interpret) "Have you changed your mind?" to spanish as "¿Has cambiado de idea?" Espero haberte ayudado :)

¿Has cambiado de idea? o ¿cambiaste de parecer? are more commun phrases than using the personnal pronouns "tú", which is tacit, and determinate article "la" with the noun mind/"mente". e.g. ¿cambiaste de idea?. It works for you?