Mohit said that his brother had won a trophy that day. When we change a sentence from direct speech to indirect speech, we need to make a few key changes.

Introduction to Indirect Speech:
Indirect speech, also known as reported speech, is used to report what someone else has said in our own words. When converting a sentence from direct speech to indirect speech, we generally make changes in the tense, pronouns, and adverbs to reflect the speaker's original words.

Steps to Convert from Direct to Indirect Speech:

Step 1: Identify the introductory verb
In this given sentence, the introductory verb is "said". It is important to note the reporting verb as it indicates that the sentence needs to be converted into indirect speech.

Step 2: Change the pronouns
In indirect speech, we usually change the pronouns to reflect the speaker's perspective. In this case, "my" needs to be changed to "his" to match the perspective of Mohit's brother.

Step 3: Change the tense
When converting from direct to indirect speech, the tense of the verb usually changes to reflect the time shift. In this sentence, "has won" needs to be changed to "had won" to indicate that the action happened in the past.

Step 4: Change adverbs of time and place
If there are any adverbs of time or place in the direct speech, they may need to be changed in indirect speech. In this sentence, there are no adverbs of time or place, so no changes are necessary.

Final Indirect Speech Sentence:
Mohit said that his brother had won a trophy that day.

Conclusion:
When changing a sentence from direct speech to indirect speech, it is important to identify the reporting verb, change the pronouns to match the speaker's perspective, adjust the tense to reflect the time shift, and modify any adverbs of time or place if necessary. In this case, the sentence was successfully converted into indirect speech by following these steps.

Mohit said , "Today my brother had won the trophy