Reported Speech

Normally, the tense in reported speech is one tense back in time from the tense in direct speech:
She said, "I am tired." = She said that she was tired.

Phrase in Direct Speech	Equivalent in Reported Speech
Simple present	Simple past
"I always drink coffee", she said	She said that she always drank coffee.
Present continuous	Past continuous
"I am reading a book", he explained.	He explained that he was reading a book
Simple past	Past perfect
"Bill arrived on Saturday", he said.	He said that Bill had arrived on Saturday.
Present perfect	Past perfect
"I have been to Spain", he told me.	He told me that he had been to Spain.
Past perfect	Past perfect
"I had just turned out the light," he explained.	He explained that he had just turned out the light.
Present perfect continuous	Past perfect continuous
They complained, "We have been waiting for hours".	They complained that they had been waiting for hours.
Past continuous	Past perfect continuous
"We were living in Paris", they told me.	They told me that they had been living in Paris.
Future	Present conditional
"I will be in Geneva on Monday", he said.	He said that he would be in Geneva on Monday.
Future continuous	Conditional continuous
She said, "I'll be using the car next Friday".	She said that she would be using the car next Friday.

You do not need to change the tense if the reporting verb is in the present, or if the original statement was about something that is still true, e.g.

• He says he has missed the train but he'll catch the next one.
• We explained that it is very difficult to find our house.

These modal verbs do not change in reported speech: might, could, would, should, ought to:

• We explained, "It could be difficult to find our house." = We explained that it could be difficult to find our house.
• She said, "I might bring a friend to the party." = She said that she might bring a friend to the party.

 Sumber: http://www.edufind.com/english-grammar/tense-changes-when-using-reported-speech/