How do I handle a co-worker that takes credit for my hard work?

First of all, I am so sorry. It must have felt bad when she did that. But there are a few things you can do if you find yourself in this situation. First, try talking to your co-worker privately and see if they're willing to share the credit. If they're not, you can talk to your boss and explain what really happened. You can also document your work so that it's clear how much you contributed. Finally, try to build a case for why you deserve more credit next time. This way, your boss will be more likely to give you the recognition you deserve.