Have you ever met the case that a recovered sql mdf file had the correct file name and size, but it could not be attached to sql server.If you look into the content of the recovered file using WINHEX,You will find the reason: the bytes is wrong. Here is a speacial tool only for sql database file recovery: http://www.tomsqlrecovery.com/sqlmdf.zip. It searchs mdf pages in disk and reorganizes them to mdf file
For Scan disk ,Right Click and Run the exe file as Administrator
For Other SQL recovery scenarios such as delete rows recovery,drop table recovery, corrupted SQL database recovery .You can Try this software: http://www.tomsqlrecovery.com/mdfview.zip.