wawaf I'm wondering whether a reinstall help?
If there's a chance that your installation was borked ... and I note that your your first installation attempt ran into trouble during the installation of the Symphony translator component ... then it's definitely worth trying.
wawaf delete all the files under installation directory?
Yes ... the installation directory should be empty, just as after your first installation attempt.
wawaf How to remove the database stuff?
I usually just delete the database and create a new one.