so what happened was. im playing mkds and i insert and take out the cartridge like 4 times then when i go and launch up the game. it said that it couldnt find any data or save file. so i boot it up again and all my data is just reset.

does anyone know how to get my save back or somehow import a 100% save file onto my ds? if yes. that would help me so much.

Did you have a back-up of your save file? I know there is tools out there to put the save on the cartridge otherwise I am sorry to say that you lost your save file.