A "?" in a date field typically means non-date data have been stored there (something that doesn't pass type validation). You can sometimes see what's there by clicking in the field so it expands. But if it's bad data, there shouldn't be a need to recover it; just null it out.
there are several reasons for a field to show "?" instead of the data desired.
field size is too small to display (numbers, dates, time)
the data is not valid for the type (this can happen when importing data, for example)
if the field is a calculation, the result may be "?" because of some error
the record may be corrupt in some way (deleting and recreating may help)
how to check:
click INTO the field, if you see more of the data, then the size is likely the problem
or you may see the invalid data (by type)
select all in the field and copy, pasting into any text editor to verify what data may be there
export the single record as .csv and open with text editor or Excel to see what is in that field
then let us know what you discover
I have clicked into the field, expanded the fields size and exported the data into .csv and opened in excel. For all the cases, the data for that particular record appears to be ?
Then I would say it may be a corrupt field or record. If clearing & re-entering the field does not work, delete the record and re-enter the entire record.