Well there is a lot more to the file than just the first few lines. Something must have happened to it. If you have a current backup I would restore it. If not then you need to double check at least a few more lines. Then you can go into your control panel and check the rest of it.
A few lines down you will find
'FULL_URL' => 'Full URL to Main Directory',
'BASE_URL' => 'Relative URL to Main Directory',
'FULL_PATH' => 'Absolute PATH to Main Directory',
