What is the best thing to say to mend things when I was the one that wants to end it, but I changed my mind?

I love him, been with him 2 years. We got in a giant fight and I went to break up with him and gave him the necklace he gave me back to him. but we talked ad he went to work but said if you don't text me or call me later, I get it.
well I want to be with him, I just don't know the right words.