Can't log onto W2000Prof

I was having some minor troubles with my printer one day
and decided to shutdown my computer after a lengthy period
of frustration. The next day when I rebooted I could not
log onto Windows 2000 Professional. I recieved error
messages that said make sure that your username, password,
and domain are correct. An error that could stem from
chaning a password, an expire date, etc. I did not change
the password and it was set to never expire. Any how, I
have a partitioned hard drive. I installed another
windows 2000 OS on the partition opposite the original OS
so that I could retrieve files. In doing this I cannot
use any of the software that is on the original
partition. My guess is that it is somehow registered to
the old or original version of windows that I originally
had my problem with. My question is, is there any way
that I can either reset my password or to reinstall
Windows over the older version with the password problem,
while still being able to access and use the software that
I had installed on that particular OS. Thank you.