Need Access to Old User Account Upon Reinstall XP

Had problem with XP Professional not rebooting, so re-
installed program. Now I find that I have a new User
Account with access to none of the programs I've
installed. How do I get the new WindowsXP program to
recognize my old User Account which no longer appears in
the list of User Accounts?

I would like to have the computer startup in my old user
account.

Cordially,

Russ