Went to the doctors with swollen ankle and foot. he said it wasn't anything but i had strangulated op for hernia 3wk?

Depends: What kind of surgery? If inguinal hernia you need evaluation for thrombophlebitis vs lymphedema. Seek advice.

DVT or normal : Not sure exactly what the question is, but if you had an operation 3 weeks ago, and you have swelling in your ankles and feet, it is probably a normal part of the recovery. If it is only on one side, or persistent, i would get an ultrasound of the legs to make sure you don't have a deep vein thrombosis or dvt. While uncommon, they can be fatal if not detected and treated.