Undo and Redo
From Vim Tips Wiki
To undo recent changes, use the undo command:
u: undo last change (can be repeated to undo preceding commands)
Ctrl-R: Redo changes which were undone (undo the undos). Compare to '
.' to repeat a previous change, at the current cursor position. Ctrl-R will redo a previously undone change, wherever the change occurred.
A related command is:
U: return the last line which was modified to its original state (reverse all changes in last modified line)
U is not actually a true "undo" command as it does not actually navigate undo history like
CTRL-R. This means that (somewhat confusingly)
U is itself undo-able with
u; it creates a new change to reverse previous changes.
U is seldom useful in practice, but is often accidentally pressed instead of
u, so it is good to know about.
 See also
- Recover from accidental Ctrl-U, which explains what constitutes a change which can be undone.
- Using undo branches, which explains Vim's unique and very powerful undo tree.
nnoremap U :echo " < < ===== C H E C K C A P S L O C K ===== > > "<CR>