Sentences which cannot be changed into passive voice

Transitive and intransitive verb

A verb can be either transitive or intransitive. A transitive verb needs an object (in sentence) to give complete meaning while intransitive verb does need an object (in sentence) to give complete meaning. 
For example,

Transitive verb.
      He sent a letter.
  (Send is a transitive verb and it needs an object i.e. letter to express full meaning.)

Intransitive Verb.
       He laughs.
      (Laugh is an intransitive verb and it does not need object for expressing full meaning.)
    e.g. Sleep, go, reach, sit, die, are examples of intransitive verbs.

Intransitive verb cannot be changed into passive voice

The sentences having intransitive verbs (belonging to any tense) cannot be changed into passive voice. The reason is that there is not any object in such sentences and without object of sentence passive voice is not possible.

A sentence can be changed into passive voice if it has subject and object. Sometimes subject may not be written in passive voice but it does not mean that it has no subject. Such sentences have subject but the subject is so common or familiar or known that if even it is not written in passive voice, it gives full meaning.
For example
Cloth is sold in yards.   

The following tenses can also not be changed into passive voice.

1. Present perfect continuous tense
2. Past perfect continuous tense
3. Future continuous tense
4. Future perfect continuous tense