Will I lose my programs if I reinstall MAC OS X?

I wanted to change the administrator username but don't know the password, so I was told to reinstall MAC OS X. However, I'm not sure if reinstalling would delete certain programs that I don't want to lose. Thanks in advance.
Update: I just put in the Mac OS X Install disc, and apparently I can't reinstall without knowing the admin password. Again, I don't know what my password. What do I do?
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