2 sentensces are they O.K?
In Canada they speak not only English but also French, by knowing only one of these languages you can for sure communicate

or maby:

In Canada is spoken not only English but also French, by knowing only one of these languages you can for sure communicate

and the second one:
Must you really have talked to him, as I said you this will change nothing?

Question

2 sentensces  are they O.K?
In Canada they speak not only English but also French, by knowing only one of these languages you can for sure communicate

or maby:

In Canada is spoken not only English but also French, by knowing only one of these languages you can for sure communicate

and the second one:
Must you really have talked to him, as I said you this will change nothing?

Answer

The first sentence is closer. I would phrase like this:
In Canada they speak not only English but also French. By knowing at least one of these languages you will surely be able to  communicate.

Possible wording for the second question that sounds a more like something you would hear (at least in the U.S.):
Did you really have to talk to him? As I told you, this will not change anything.