My 30 year old son's girlfriend just broke up with him. How can I force her to take him back?

I've been calling her and texting her nonstop but I think she might have changed her number. She unfriended me on facebook and has blocked me on twitter. I just want to talk to her and explain that my son is the best thing she will ever have and she's being very immature and ignoring me. I've tried calling her parents at work and if they didn't leave in another state I'd drive over there and talk to them face to face. I am very distraught because I thought they would get married and make me a grandmother. She almost moved in with us and lived with my son in the basement. She used to talk about their future together. I'm debating whether or not to surprise her at work or ambush her at her apartment after work. I just want her to be rational about this. She's making a huge mistake and it needs to be nickled in the buck.