You can try reactivating dev mode, setting the dev password, and then re-keying from a prior package file (if needed).
Home 3x, Up 2x, Right, Left, Right, Left, Right
If you don't have a previous packaged channel app you worked on then the key you create doesn't matter - but you'll need to create one on the roku device with "genkey" after you enable dev mode.
The screen can be touchy to get it to display - the key presses need to be timed. It took me 8 tries last time I had to do it because the roku home screen slows down and animates when pressing the left/right sequence.