Error details: Could not resolve host: libraries.minecraft.net

Dear MOJANG,

I am trying to open Minecraft launcher to play some Minecraft and when I click the play button it shows me this. I can not play Minecraft and I don't know why.  I searched in YouTube about my problem and I found some videos but they didn't help me actually because all the videos that I watched tells me to copy paste the link that the screenshot says to google and download the file but when I try to do this it shows me an error page in google:

https://errors.net/error/?error=nx&domain=libraries.minecraft.net

I really don't know what to do because I tried a lot of things to do. please help me to play Minecraft. By the way when I click to close the error page on Minecraft launcher and click play again, I can play Minecraft but I don't have sound on the game neither sound or music. so please help me about my problem.

Thanks for your support,

Moxitas45

Stavros