Need a way to switch specific data from columns

Basically I have 635k records in a table with a person's first name, and date of birth (other stuff but it's not relavent). I imported all the data from excel files, but somehow a bunch of records got the first name and date of birth mixed up, so I'm trying to write a stored procedure that would switch the first name with the date of birth wherever the firstname is purely numeric, or something of the sort. Now records are in fact repeated so another possible but more time taking solution is to write a stored procedure that I give the date of birth and it does the switching around for the respective date of birth when it's found inside the First name. Any suggestions? All the code I've written has proved useless :/

so I'm trying to write a stored procedure that would switch the first name with the date of birth wherever the firstname is purely numeric, or something of the sort.

If you have an ID column all you would need to do is check if there are multiple records (count(*)> 1). if so keep the first one (min(id) or whichever you choose), delete the rest, get the two values into local variables and update the record in hand.
if you already made an attempt post some code and we can help you out.