“我迟到了”这么说——>

I'm sorry I'm late. 真抱歉我迟到了。
Sorry to have kept you waiting. 很抱歉让大家等我一个人。

如果是自己开车，理由非常多：

I ran out of gas. 我要去加油。
I got lost. 我迷路了。
I don't have GPS. 我没有全球定位系统。
I missed my exit. 我错过了高速（高架）出口。
There was construction. 碰上修路了。
There was an accident. 遇上车祸了。
It was farther than I thought. 这地方比我想得远多了。
I couldn't find a parking spot. 我找不到停车位。

如果不是自己开车，大众交通工具更容易摊上事：

I couldn't get a taxi. 我打不到车。
The bus was late. 公交车晚了。
I missed the bus. 我没挤上公交车。
I was stuck in traffic. 遇上堵车了。

交通状况我控制不了，生病我也控制不了啊：

I feel sick. 我病了。
I don't feel well. 我不舒服。
I'm a little under the weather. 我身体有点不适。
My skin is breaking out. 我皮肤过敏了。
I'm dizzy. 我头晕。
I'm so dizzy I can't stand up. 我晕得站也站不起来。
I have a headache.=My head hurts. 我头痛。
I feel sick to my stomach. 我胃痛。

这还不算，我有时是活雷锋，我要帮助别人啊。
我是有朋友的人好吗，我要帮朋友好吗：

I had to drop someone off. 我要送个朋友。
My last appointment ran over. 我上一个约会耽搁了。

实在不行，我承认我是个不靠谱的人好了吧，睡过头什么的也不是没发生过。
我就是这么不靠谱一人怎么着：

I overslept. 我睡过头了。
My alarm didn't go off. 我的闹钟没响。
I misjudged the time. 我看错时间了。
I lost track of time. 我忘了时间了。
I had to get money. 我去取钱了。
I had to run an errand. 我有事要办。