Which of the following sentences is/are correct which refers to English speaking of "Are you still worried about the future"?
- ¿Todavía te inquietas por el futuro?
- ¿Todavía inquietas por el futuro?
- ¿Todavía inquieta/o por el futuro?
Naturally, you would use it as an adjective like this:
This is exactly the same as the original sentence you want to translate, the verb is "to be" and "worried" an adjective.
If you still would like to use the verb "inquietar", the subject is the thing worring you, in this case, "the future". So, your two first sentences are not correct. Usually, you use a pronoun for expressing who worries the thing (indirect object), as you tried in your first sentence with "te". So the sentence would be: