When you type commands, text jumps around on the screen and
nothing works the way it's supposed to.
Make sure you're not typing the J command when you mean j.
You may have hit the
CAPS LOCK
key without noticing it.
vi is case-sensitive. That is, uppercase commands (I,
A, J, etc.) are different from lowercase commands
(i, a, j), so all your commands are being
interpreted not as lowercase but as uppercase commands.
Press the
CAPS LOCK
key again to return to lowercase,
press
ESC
to ensure that you are in command mode,
then type either U to restore the
last line changed or u to undo the last command.
You'll probably also have to do some additional editing to fully
restore the garbled part of your file.
When you type commands, text jumps around on the screen and
nothing works the way it's supposed to.
