I have the Rocksmith 2014 Remastered bought in steam and i downloaded the dll and putted it in the RS folder but there wasn`t a D3DX9_42.dll to replace. I played the game and the cdlc`s that i have in the dlcs folder don`t appear. If any can help me i would be so grateful  ;)

You need to buy cherub rock.

 

https://store.steampowered.com/app/248750/Rocksmith_2014__The_Smashing_Pumpkins___Cherub_Rock/

Maztor is correct, that is the simplest solution. You can also DL Custom Forge Song Manager and change the App ID of all the CDLC you download to an ID of a DLC you already own. It is under the Custom Mods drop down on the Song Manager tab. Should be the first drop down option.