I am running the trial version of Movie Studio 15, and the following has happened. I have created a 1:25 minute-long sequence. The cursor was at the end of the sequence. I accidentally hit "j" on the keyboard, not understanding the JKL key functions. The cursor went into reverse "scrub" mode, looking like it was behaving like it should. However, all the assembled clips it traveled across were then blacked out, with sound only. I cannot find a way to reverse this effect. Although I managed to stop the reverse review 2/3 of the way back over my edited sequence all the sequence is now blacked out except the first couple of frames of the very first clip. Worse, the clips in the project media holding box have images on them but play only sound. I then went to start from scratch, setting up a new folder of the same .MOV video clips taken from my original file and opening a new page in Movie Studio 15. The new copies of the same clips now play in the new version, but the last two clips in the numerical sequence download into the new media holding area with a green-screen contents image only. This looks like a virus on the keystroke J, but might be me not understanding something. I have tried deleting the sfk files then reloading them into the project-media panel but this has not reversed the green-screen effect on these two only clips , where they sit in the project media panel. The clips themselves play OK in Movie Studio 15 when put on the timeline and have a pictorial representation of their contents on the timeline. I have also tried replacing clips in the blacked-out sequence with clips that are running ok on another edit. These remain blacked out in this faulty edit sequence. Can anyone help, please.