I have a question for you that have been going out to run with tkd . I was thinking to improve my sparring and I was thinking how long do you run.
When I was 16 I ran really much for one year couse I was training for an half marathone or 21km but I dont think that it did improve my sparring so isint it just better to run just like 3 km and much faster or maybe 5 but not much longer than that? what do you think might help with improving sparring??

i think you need both.  running long distance would be helpful in general, and running up a hill or up stairs would help with that quick reflex kicks with power.  you are not just kicking one kick at a time during sparring, you get into that brief but very intense kicking phase during sparring. 

high intensity interval training is helpful for that.  you jog lightly for 30 sec, sprint for 30 sec, jog for 30 sec, and so on.  treadmill or other stationary cardio machines have interval setting that you can use.  if you are running outside, use streets as an interval point.  so, you jog one block, sprint one block, jog one block, sprint one block, and so on.  instead of sprinting, you can also mix up with something like jogging with your knees up. 

running uphill can be helpful in both cardio/reflex.  by running, you get that cardio exercise, and by running uphill, you are constantly under more resistance. 

From all that I have read, interval training is the best way to improve your cardio health. I absolutely hate running. But... I have found that the increased stamina really pays off in sparring. I can typically outlast my opponents. this give me a huge advantage when they're sucking wind toward the end of a match and I still have energy.

Treadmills are OK. I workout at a gym and you can watch TV while you're using them. Unfortunately that treadmill is helping you to run because your feet aren't actually moving your body. To really get the cardio benefit you have to be on a track or a trail.

 There is no need to run such a far distance actually. In sparring its all about strength, speed, stamina and the speed of recovery. All you need to do is, run a constant 2-3 kilometres daily and do sit ups and push ups(if you have the time) to improve your stamina. That is very important. Your out of DOJANG training should be more on stamina rather than on speed. If you really intend to increase your kicking speed during normal leisure hours. I suggest you kicking the air at least 50 times per leg, per kick( The kick you usually during sparring)  should be enough. Trust me. In 3 weeks you will definitely see improvements. As for your Abdomen. Do sit ups to strenthen your abdomen muscles and from there you cant hardly be beaten down. try asking for a partner to train with you. At least someone is there to point out your mistakes. 

 NO PAIN NO GAIN- THE PAIN SHOULD COME IN MODERATION. NOT EXCESSIVE. YOU WILL INJURE YOURSELF