Well, first you would parse the original string into a DateTime
instance. I would call TryParse, passing the general date time pattern "g"
(assuming that your culture is "en-us").
Because the generat date time pattern is dependent on the current
culture information to determine the format of the general date/time
pattern, if you want to use an exact pattern, you would use:
d/M/yyyy h:mm:ss tt
Of course, even the above is subject to culture info, in that the AM/PM
designator is specific to the DateTimeFormatInfo on the current culture.
You would probably want to make sure that the invariant culture is used when
parsing.
Then, once you have the DateTime instance, you can call ToString on it,
passing a format of:
dd/MM/yyyy
For your output.