Do bad grades kill my chances of getting into the Ivy League Colleges?
Firstly, do you have a college advisor? If so, this is definitely a question that he/she will want to tackle. If not, I recommend finding one, as an experienced college advisor will be able to help with all elements of picking and applying to the right school.
As for your question – a few Ds certainly won’t help the cause when it comes to getting into an Ivy, but it depends on what else you have going for you. If you’re applying on your academic merit alone, then a few Ds will probably make applying to the Ivies impossible – however, if you have other elements to your application (athletic recruitment, remarkable extracurricular achievements, etc.) they might be overlooked.
Remember also that there are a lot more colleges out there than just the Ivies.
One last thing: why did you get the Ds? If there are special reasons why you received them, they might make exceptions. If not, then they could be a problem for you.