The obligatory recitation of Surah al-Fatihah and the core phrases of the prayer are recited in Arabic, as the Prophet ﷺ and his companions did. A new Muslim learns these gradually; personal supplication (dua) outside these may be made in any language.
References
Sahih al-Bukhari 756
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.