when i finish the previus quest and kill the dragon i go talk to jarl balgruf he tells me to look for the grey beards, the quest doesnt show on my journal tho, and i dont know what to do help pls. this happens to me with all characters

What system are you on? If it happens to every character you start, I'd re-install the game, provided it is installed in the first place. Do you have all of the patches?