I don't know if OpenOffice honours Excel passwords or not, but it's worth a shot I'd say. So long as the file isn't also encrypted, I'd say you have a fighting chance.
If not, start looking for some Office password cracking program. It could take some time if it has to use brute force cracking. In the future, you might want to pick a password you can remember a bit more readily.
I have some excel files password protected, but I lose those passwords.
Is it a way to open the files with out the passwords?