Hi Symon,
I’m sorry to hear about the trouble you had upgrading. For cases just like this, we wrote up a Troubleshooting Upgrades article for the wiki. Have you been able to take a look at that yet? In particular, I think the section on re-trying upgrades may be of some help.
I also took a look at my database for version 2.1.3, and noticed that there are no tables that begin with exp_files. Do you know how these were added to the database? Were they placed their by some add-ons, or were they added to the database during an upgrade process that failed? If the latter, it’s important to empty your database and then importing a database backup before trying the upgrade again.
Are you in a position where you can restore your site from backup and then try the upgrade again? That’s going to be the best route to take right now.