Vim has several advanced ways of undo the changes made in file, however, I’m not going to go into all of them here but just show you one. The :earlier and and :later command in vim can move you backwards and forwards in time through your change history. Very much like Time Machine in OSX.
Note: This is NOT a substitution for source control!
:earlier {count} Go to older text state {count} times.
:earlier {N}s Go to older text state about {N} seconds before.
:earlier {N}m Go to older text state about {N} minutes before.
:earlier {N}h Go to older text state about {N} hours before.
:later {count} Go to newer text state {count} times.
:later {N}s Go to newer text state about {N} seconds later.
:later {N}m Go to newer text state about {N} minutes later.
:later {N}h Go to newer text state about {N} hours later.
Below are some links to more information about :earlier and :later as well as other undo features.
http://vimdoc.sourceforge.net/htmldoc/usr_32.html
http://vimdoc.sourceforge.net/htmldoc/undo.html#undo-branches