Big problem

I bought Palas today.

I made a new database, put drupal 7 on the website via ftp.
Then added the package stuff and uploaded the database.
It worked during th afternoon. although, without any CSS.

Website doesn't work (php error code 500)

I used XAMPP to see the demo website.
Did everything I found in a description on this forum
It works, but when I tried to login, using admin/admin, i got an error.

Now the entire demo website doesn't work.
Reuploading the database seems to work there, but not on my website.

Whats wrong and how do I fix my website that I have at a website hoster (they limit the amount of databases you can have, and i haven't found a way to delete one.

This is a pretty big problem considering i wanted to work on the website this holiday.
and I won't have any time after that.

Anyone able to help out?

Asuna

Also, there is no Documentation included in the download from Themeforest, unlike my previous purchase.

PS:  I bought another template a year ago, and that worked fine, both for website and for the demo (even logging in)