Final answer:
The correct word to complete the sentence is 'Despite', indicating that the speaker reached on time even though they missed the train.
Step-by-step explanation:
The correct word to fill in the blank of the given sentence 'I missed the train, I reached on time.' is 'Despite'. This is because the sentence suggests that the speaker reached on time in spite of missing the train, which means a contradiction or an unexpected outcome is being described. 'Despite' is used to show that something happened anyhow, even though there were problems or obstacles. Therefore, the complete sentence should read: 'Despite missing the train, I reached on time.'