Q:

What part of speech is "no" - negative pronoun, adverb or something else?

Is "no" - a negative pronoun, adverb or something else?

There was no reply.
The song was no strain on her voice.

What do you think about this?

Negative sentences with introductory "there" are formed in the usual way for the verbs which are their predicates, that is, by means of
  appropriate auxiliaries for all the verbs but to be. In the latter
  case two negative constructions are possible:
a) either with the negative pronoun no, as in:
There was no sign of him in the hall.
There is no knowing when he will
  come...(http://doclecture.net/1-7538.html)

A:

It's not a pronoun because it doesn't take the place of a noun - not by itself anyway.  No one/nobody/nothing/nowhere would be some of the "pronoun forms" of no.
No generally modifies a noun so that makes it technically an adjective.  When modifying a verb or adjective not is used.
No is also a typically a determiner - which can be considered a special type of adjective - because it can occupy the "spot" where an article or word like this/that/these/those would go.

