Disconnect from the Internet. This may or may not be relevant,
but it will not hurt. Pull your ethernet cable or turn off
your modem -- whatever it takes. Start Money, click below the
password field to select "I want to sign in to Money directly,
without access to all online services." then click Next.
You already changed your LiveID/Microsoft ID, but that did not affect
your Money file. You must use the credentials that were in
effect at the time that you saved that Money file.
The password is case-sensitive. If you are not sure of your
credentials, write down what you remember. Consider permutations.
Check your notes. You will not get into the file without those
credentials in effect when the file was saved.
With UK Money, there is no way to remove the current ID that the Money file knows.
If you get into your file, you could do QIF exports+import into a new Money file. Not
everything will be retained, but you will have a very clean file.
