Speakers of English often use ‘I’ and ‘me’ in place of each other. The difference is actually very simple. Allow us to explain.
Let us begin with an exercise. Fill in the blanks with either ‘I’ or ‘me’ in the following sentences.

      __ want to watch a movie.

      This is the house __ want to buy.

      Sudhir and __ will go to Delhi.

      You and __ will play today.

      He asked __ to drive.

      She needs to pay __.

      He gave __ the key.

The answer to the first four sentences is ‘I’ and the last three sentences is 'me'. This is because ‘I’ is a pronoun and hence must be the subject of a verb ('I'is the first person singular subject pronoun and will always refer to the person performing the action of a verb).
On the other hand, ‘me’ is a pronoun that must be the object of the verb (me is anobject pronoun and will always refer to the person that the action of a verb is being done to.)