Failed password change, cant login anymore

Hello,

I tried to change the password of the administration account and got a message kind of “wrong password”. (Piwik is in german language)
I tried another password, a little bit simpler and got another failure message like “wrong token”. Then I was kicked out of the administration panel and can’t login with any of these three passwords.
Password reset isn’t working. “server could have disabled the mail()-function”.

So… how do I get access to my piwik installation? There isn’t any other admin.
I have access to files and database and don’t have a plan what I have to do.

The following FAQ addresses this issue: http://piwik.org/faq/how-to/faq_191/

I hope this helps.