You should still have your backup, so even if you delete the current site all is not lost. Before even worrying about getting the old site you created already in there, you should concentrate on making sure that it works at all. Once all that is done THEN start customizing it.
You can try some of the things that are mentioned in this site. I found it when I googled the error you were getting.
If you have already tried to import your old wordpress content before getting wordpress working in general, then you have made a mistake. This is what your site should look like when its working. If you never saw this then you should delete what you’ve done so far (but don’t delete your backup of course) and start over. Then later on you can import the content from the backups you created. That’s assuming you exported and backed up the content as I suggested.
Or you could always just buy that program that you were using in the first place, but that would be last resort.