Hurt knee after jump roping wrong way.went doctor said inflammed.been using rice method and nsaid feels better. been 2weeks. can it heal that fast?

It is possible: I am glad you are feeling better. How long it takes to heal depends on the severity of the injury. Thankfully, it sounds like you did not injure it too severely. You could start up your exercise slowly and cautiously. If no pain, that is good. If it doesn't feel quite right or starts to hurt, give it more rest before starting again.