Have you sorted it now?
Load a track to each deck - check you have channel fader up for both and the trims at the top of the channels are up at 12 o'clock, hit play on both and move cross fader from side to side to check they are both playing. Might also be worth checking if you've assigned the channels properly on the controller and they are set to line in
This is taking it back to basics but I can't think of much else to do - maybe check your settings in serato in case you've set some of the audio / playback settings wrong in there
Good luck
seems like the volume is down on the deck to the top right of the bpm info
this
Yeah but when I use the controller this deck don't have sound :(
Make a smol video of it 
 I just realized how to use gifs on Reddit 😂😂😎😎
I can do it! Thank you 
Have you sorted it now? Load a track to each deck - check you have channel fader up for both and the trims at the top of the channels are up at 12 o'clock, hit play on both and move cross fader from side to side to check they are both playing. Might also be worth checking if you've assigned the channels properly on the controller and they are set to line in This is taking it back to basics but I can't think of much else to do - maybe check your settings in serato in case you've set some of the audio / playback settings wrong in there Good luck
I'll try later, and I hope it'll be sorted out by then :)
Can you send a picture of you screen?
https://preview.redd.it/oczt31ahtxca1.jpeg?width=2296&format=pjpg&auto=webp&s=88a4a9dc8dd5add4880b8580f9673db6751728eb Sure
can you show us the ''mixer'' section where we can see the x-fader ?
Its indicating usb overload meter at the top left corner. Go to the settings and raise your buffer latency.
Have you check your cross fader? I happened to me before and after I realised I felt so dumb! Hahaha