ITunes randomly greyed out all my iPhone music/video! PLEA

Hi, ive been using my iPhone like normal and yesterday added a song to my phone. And everything was perfect. I did nothing new or different on my phone or computer. And I went on it today to add an album and its all greyed out. All my music and videos. I can’t even play them on iTunes but on my iPhone itself, nothing is wrong.
Its the same computer so I don’t know why its doing that. I usually have “manually manage music and video’s” ticked and now its unticked. And when I go to tick it, it tells me its going to erase all of my content on my phone.
Does anyone know how to solve this problem? (soon) without erasing all of my content. its really annoying!! Why is it doing this?!
(its a jailbroken iPhone btw)
Answer #1