你好！
上次我在山西工作单位的时候，也就是前20天，你给我打了一个电话，说你帮我联系了工作，就是你工作的初中学校，让我去应聘一下，当时我说第二天就来北京，但我没有想到当我向学校最后告别的时候，领导又变卦了，说教育局要检查，又让我再等几天，而我又不知道究竟让我等多久，所以没有及时和你联系，真是不好意思！我刚返回北京，现在想知道你们学校还需要老师吗？顺祝你天天快乐！

Dear XX,
It was glad to talk with you last time via phone. I really appreciate it. At that time (around 20 days ago), I was at the working place in Shanxi. If I am not mistaken, you were helping me with job hunting, and you told me to have an interview at the secondary school where you were working. I said I would come to Beijing the next day. To my astonishment, the school leader suddenly changed his mind, when I was saying goodbye to him, arguing that the Education Bureau was conducting an inspection, and asked me to wait for another couple of days. I didn't know the exactly number of days that I had to wait, and that's why I didn't contact you in time. I am really sorry about this and hope your kindly understanding.
And here I am in Beijing now. I wonder, whether I still can have the chance of interview you mentioned last time or not?