How do I message her? What do I say? (16yr old)

Hi, I'm a 16 year old teenager and I need help with messaging my crush. We haven't been in contact for about 2 years (long story, would take long to explain). So here's the question, how do I message her after a 2 whole years of non-messaging and no contact? I feel like me hitting her up in dms with "Hey" would seem weird because we haven't spoken in 2 years and I don't know really how to start a convo or anything. She's 15 years old and she is interested in medical education, that's all I know. I have her on both snapchat and instagram.

Could someone give me an advice how to message her first, how to start a convo, generally how to keep her interested in talking with me. Meeting up with her to hang out should be easier (at least I think) so I really only need the texting part advice, the beginning. And no, we aren't in any kind of a beef, we just lost contact. I'm just a teenager and I realize that this is a very dumb question compared to others, but someone please help me. ?

Thanks 🙂