I think you have to decide what's really in those cells first.
If the values were entered as text, then changing the format of the cells to
General will still leave the value as text. But with the next change (even just
F2|Enter), excel will see it as a date.
So the first thing I'd do is try to reenter those values so that excel could
interpret them as dates.
Ctrl-a (twice in xl2003) to select all the cells.
edit|replace
what: - (hyphen)
with: - (hyphen)
replace all.
Depending on your computer's date format and the values in the cells, you may be
almost done.
I'd format a few of the cells using an unambiguous date format: dd-mmm-yyyy
(for example).
Then you can see if values got converted to dates correctly.
If they did, format them the way you want (yyyy-mm-dd).
But if it tried to convert 12-7-1997 into December 7, 1997 and you wanted July
12, 1997, you have more work to do.
One way that you could try is to convert your pc's short date settings to the
format that you want.
close excel
windows start button|settings|control panel|regional settings applet
Date Tab (fix that short date setting)
(I use win98, so your steps might be slightly different.)
Then back to excel and try it out again.
If it worked ok, then close excel and change your regional settings back to the
way you like them. (I didn't actually have to close excel, but it couldn't
hurt!)
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Another way if your data is laid out nicely in columns is to select a column
(it's one column at a time).
Then data|text to columns
choose delimited (uncheck everything)
tell excel that the field should be mdy or dmy
This is the "format" of the current values--not what you want.
and finish up by putting it in the same location.
(You can change the format to what you really want later.)
Then do the next column, and the next, and the next....
