Probably a moot point, but
I don't use filezilla so I do not know if this option is availible to you or not. With my FTP client program (FTP Commander) there is an option to mask/unmask the password (this will not provide the actually password used for the server if it has changed, but will help in figuring out typos when you enter the information.. I know there are times I hit the wrong key (or accidently enable the caps lock while typing)..
Does your server have a cpanel or other type of interface where you could reset the password...