Password Denial

While attempting to transfer Outlook Express 6 data from
an older p.c. to my new p.c., the program will not allow
me to use my password to access the information. The
error message reads, "Password not valid"...when, in fact,
it was valid earlier in the day. Is there anything that I
can do to retrieve that information ? Any way that I can
get the password deleted ?
Please help !