Doctor prescribed me sulfamethoxazole/trimethoprim 800mg/160mg to treat a stye, will that work? i've had it for 1month, it popped but came back

Have it checked: If it came back, I would be concerned that it may not be just a stye. It could be a chalazion, which is an inflammation in one of the oil glands that may need to be incised, or something else. I'm would suggest seeing an ophthalmologist who should be able to help you.

Depends: If you have an associated infection of the soft tissue around the stye, then the Bactrim (sulfamethoxazole and trimethoprim) can provide reasonable anti-infective coverage. But it sounds like you may need to see an opthalmologist for a possible incision and curettage.