Ube to replace indexed field

I am writing a UBe in 9.1. to replace an indexed field with new one. There are six indexed fields in the table out of which one column is and old one that needs to be replaced. I dont find another standard index for this table so I am not finding a way to update the record. I can try select and fetch next and would be able to get the old record, however I wont be able to update since the field is an indexed field with a prefix of *.