Thank you for your help!
I didn't want to reinstall everything, so what i did was in the database i changed the "email" address for admin in the "mdl_user" table, so i could send myself a new password.
But also works, if you just change the "password" in the same table to something md5-coded string. (Just clearing is not enough..) (4 exmpl: md5("admin") = 21232f297a57a5a743894a0e4a801fc3, or just copy from another user, where you know the passwd). (I tried for a user, not for admin and worked just fine..)
Thx again, jg