If you re-formatted your hard drive it is unlikely that you will recover your files, particularly if you did a low level format. I am not sure what you mean by "repeat overwrite". If you mean the deletion of single or even multiple files without re-formatting, then the answer is that it has a minimal effect on your drive's speed. However defragmenting the drive will usually restore any speed loss.There are a number of free open source programs that say they can recover deleted files. Go to "SourceForge.org".