This is a very good question! It's one of those English language things that one just has to learn, because it's the expression we native English speakers use. However, let me offer a possible difference between the two prepositions here: Locks to rooms and houses can be changed, and often are changed for a new owner or tenant. So the key to these locks is "to" the room, now. "Of my room" implies the key is permanent and would never change. If this drives you nuts, you can also say, "I've lost my room key," which keeps you from trying to remember which preposition to use. Hope this helps and doesn't make it more confusing!

"To my room" is correct. Sometimes the best answer is, "Just because that is the way we say it."

Your thinking is correct, English is like that. Still, to become comfortable with the languange you have to adjust to the nuances. So think like this, if referring to an object that is being turned on/off, is activated by, or opened/closed by another object. The words “to” or “for” is what you would use

“To your room” is collect because it’s a preposition. You are guiding the audience to the topic your talking about.

i don't know. What's that mean