No, you don't necessary fail ninth grade.. you just have to work harder to make up the credits you missed..
You will still be a sophomore when the new year comes up, but your going to have to go onto E-school and do classes on the internet..
They let you do this from detention in school... By staying after school on some selected day's and that you can make it in...
But it is usually after school everyday until you make that credit up..
See I never had to do this..
I was an A-B+ student all of high school..
I dot one D.. But that is because I had a skating accident that about took my life..
The two months I was in coma at the hospital made me fail that final..
While all the other teachers let me make up everything...
So just work hard man... study as hard as you can...
You will be able to pull yourself out of the hopper..