J1 to F1

hi. my name is serap. i have a j1 viza and it is expired like 14th of september and now i have just 7 days left to stay in the us as legally. i want to change my viza to f1 without going to my country. is it possible to stay here as legally till i get my f1 viza? but i have not applied to school yet. is it too late?
thank you...

If your visa is expired, you are out of status and here illegally.

You need to consult with an immigration attorney and get your visa status sorted out right away.