Major database problem

I wanted my blog’s pages to load faster, so I changed the wp-config.php file, adding two lines. One was a comment. The other activated caching. Stupidly, I did not back it up.

I was able to log in and do things, but I got some errors when I saved my changes. Then, I read some threads here and removed some blank lines after the last php statement and also the two lines I had added. Now, when I tried to log in I’m being told that my user ID and password are wrong.

Fortunately, I have my mySQL file backed up and my theme files.

Is there a way I can fix my problem without much risk of worsening it?

My blog is here.