Data recovery is not 100%. Sometimes, you cannot recover anything at all, so in this case, you'd simply replace the hard drive with a new one and restore the data from the backup that you keep.
In cases where software-based data recovery doesn't work, your next option is professional data recovery -- which can run into the thousands of dollars depending on what they've gotta do to recover the data.
www.drivesavers.com is a great company -- they're fast and good, and their prices are reasonable (and yes, one thousand dollars is a reasonable cost for recovering data off of a dead hard drive -- it just depends on how much the data is worth to you).
I would suggest simply purchasing a new hard drive (that'd be less than $200) and just using your backup that you keep to restore the data you need.