Swollen ankle for weeks and no pain. what kind of joint problem could it be?

Doubt joints: Joint disease usually hurts. Painless swelling is more suggestive of edema due to fluid retention. Causes include kidney disease, heart failure, liver disease, or blood clot. There is something called benign essential edema. As the name indicates, it is a benign condition usually in both ankles. If it is only one ankle problem you need ultrasound to rule out a blood clot in leg veins.

Unlikely joint: Ankle swelling is pretty non-specific. If you are having ankle pain either when standing on your foot, by pressing on the joint, or when ranging there may be a joint injury. Swelling without pain can be from fluid overload (kidney failure, heart failure), lymphedema, or swelling from varicose veins. A physical exam, a good history and a x-ray can help sort this out. Compression socks will help.