I think OP is asking if there is a way of looking back at changes made to logins.

If so, and you have the default trace running, it can be done as long as the change wasn't too long ago.

I use this:

use master;

set nocount on;

declare @path nvarchar(500)

if HAS_PERMS_BY_NAME(NULL, NULL, 'ALTER TRACE') = 1

select @path = convert(nvarchar(500), value)

from ::fn_trace_getinfo(0) i

join sys.traces t on t.id = i.traceid

where t.is_default = 1 and i.property = 2;

if @path is not null

begin

select @path = reverse(substring(reverse(@path), charindex('\', reverse(@path)), 500)) + N'log.trc'

select last_occurrence, name + isnull(' (' + subclass_name + ')', '') EventName,

DatabaseName, LoginName, RoleName, TargetUserName, TargetLoginName, SessionLoginName, TextData, num_occurrences

from (

select e.name,

v.subclass_name,

df.ApplicationName,

df.DatabaseName,

df.LoginName,

df.RoleName,

df.TargetUserName,

df.TargetLoginName,

df.SessionLoginName,

convert(nvarchar(255), df.TextData) TextData,

max(df.StartTime) last_occurrence,

count(*) num_occurrences

from ::fn_trace_gettable(convert(nvarchar(255), @path), 0) df

join sys.trace_events e ON df.EventClass = e.trace_event_id

left join sys.trace_subclass_values v on v.trace_event_id = e.trace_event_id and v.subclass_value = df.EventSubClass

where e.category_id = 8

and e.trace_event_id <> 175

group by e.name, v.subclass_name, df.ApplicationName, df.DatabaseName, df.LoginName, df.RoleName, df.TargetUserName, df.TargetLoginName, df.SessionLoginName, convert(nvarchar(255), df.TextData)) x

order by last_occurrence desc

end

Hope this helps.