The Article of Reported Speech

Reported Statements

When do we use reported speech? Sometimes someone says a sentence, for example "I'm going to the cinema tonight". Later, maybe we want to tell someone else what the first person said.
Quoted speech refers to reproducing another person’s exact words. Quotation marks are used.
Reported speech refers to reproducing the idea of another person’s words. Not all of the exact words are used: verb forms and pronouns may change. Quotation marks are not used.

Quoted speech:
Jane said, “I am hungry.”

Reported speech:
Jane said that she was hungry.

Notice in the example: the verb form and pronoun change from quoted speech to reported speech.

Tense / Modal
Simple present
Quoted speech: He said, “I like ice cream.”
Reported Speech: He said (that) he liked ice cream

Present continuous
Quoted Speech: He said, “I am working hard.”
Reported Speech: He said (that) he was working hard

Simple past
Quoted Speech: He said, “I bought a car.”
Reported Speech: He said (that) he had bought a car

Past continuous
Quoted Speech: He said, “I was walking along the street.”
Reported Speech: He said (that) he had been walking along the street.

Present perfect
Quoted Speech: He said, “I have worked hard.”
Reported Speech: He said (that) he had worked hard.

Past perfect*
Quoted Speech: He said, “I had taken English lessons before.”
Reported Speech: He said (that) he had taken English lessons before.

Future (will)
Quoted Speech: He said, “I will work hard.”
Reported Speech: He said (that) he would work hard.
Future (to be going to)
Quoted Speech: He said, “ I am going to work hard.”
Reported Speech: He said (that) he was going to wok hard.

Can
Quoted Speech: He said, “I can work hard.”
Reported Speech: He said (that) he could work hard.

Should
Quoted Speech: He said, “I should call my mother.”
Reported Speech: He said (that) he should call her mother.

May
Quoted Speech: He said, “I may work hard.”
Reported Speech: He said (that) he might work hard.

Must
Quoted Speech: He said, “I must study on Sunday.”
Reported Speech: He said (that) he had to study on Sunday.

Have to
Quoted Speech: He said, “I have to work hard.”
Reported Speech: He said (that) he had to work hard.

Ought to
Quoted Speech: He said,”I ought to work hard.”
Reported Speech: He said (that) he ought to work hard.

Informal: sometimes, especially in speaking, the verb in noun clause is not changed if the speaker is reporting something immediately or soon after it was said.
a. immediate reporting:
A: what did Ann just say? I didn’t hear her.
B: she said (that) she is hungry
b. Later reporting:
A: what did Ann say when she got home last night?
B: she said (that) she was hungry.
Occasionally, we don't need to change the present tense into the past if the information in direct speech is still true (but this is only for things which are general facts, and even then usually we like to change the tense):
• Direct speech: “The sky is blue”
• Reported speech: She said that the sky is/was blue

Reported questions

How can we make the reported speech here?
In fact, it's not so different from reported statements. The tense changes are the same, and we keep the question word, for example:
• Direct speech: "Where do you live?"
• Reported speech: She asked me where I lived.
Do you see how I made it? The direct question is in the present simple tense. We make a present simple question with 'do' or 'does' so I need to take that away. Then I need to change the verb to the past simple.
So much for 'wh' questions. But, what if you need to report a 'yes / no' question? We don't have any question words to help us. Instead, we use 'if':
• Direct speech: "Do you like chocolate?"
• Reported speech: She asked me if I liked chocolate.

Reported Requests

There's more! What if someone asks you to do something (in a polite way)? For example:
• Direct speech: "Close the window, please"
• Or: "Could you close the window please?"
• Or: "Would you mind closing the window please?"
All of these requests mean the same thing, so we don't need to report every word when we tell another person about it. We simply use 'ask me + to + infinitive':
• Reported speech: She asked me to close the window.
Some verbs are followed immediately by a (pro)noun object and then an infinitive phrase. These verbs (see the list below) are often used to report speech.

Reporting speech: Verb + (Pro)noun object + infinitive*
Advise someone to invite someone to remind someone to
ask someone to Order someone to tell someone to
encourage someone to permit someone to Warn someone to

*Other common verbs followed by a (pro)noun object and an infinitive:
Allow convince instruct beg direct persuade challenge expect Urge

To report a negative request, use 'not':
• Direct speech: "Please don't be late."
• Reported speech: She asked us not to be late.

References:

Azar, Betty Schramper. 1992. Fundametals of English Grammar, Edisi Dwibahasa(Budijanto, penerjemah.). Jakarta Barat: Binarupa Aksara.

http://www.perfect-english-grammar.com/reported-speech.html