Nearly any decent data recovery tool can help you if you simply need to undelet files. Since a file is not actually deleted to begin with.
1. When you "delete" a file, the OS removes the header information from it. This essentially orphans the file to be written over when space is needed. If the drive can be read as a slave, almost any program can find thos orphaned files and write new headers, essentially "reviving" the file and linking it back to the file system.
2. If the Master boot record was deleted, follow the instructions here"
http://pcpropaganda.wordpress.com/20...ot-record-mbr/
to write a new MBR. That will allow the drive to be a bootable partition and access the windows system file again.
3. Worst of all is corruption or loss of the file system table. The % this happen to is so small as to be unrealistic. This would involve the drive being seen by the BIOS, spinning up, being seen by windows, but major kernal panics if you try to double click on the drive. I have never seen it where copying 5+ gigs and a kernal panic where not involved. If that is the case, you would need a data carving utility like foremost for linux. It's the kind of tool the FBI and NSA use for reviving lost infoormation from a recovered data disk. It's not within the realm of 99.9% of casual users and is linux command line only. If someone knows of a windows data carving utility, please mention it, as it may be easier to use.
I would recomend trying 1 & 2. If the data is of great personal importance (and I mean SEC required financial statements, HIPA Records, Legal Documents in a pending trial, etc) then pay for proffesional recovery. If what was lost is divx movies, mp3's, and old term papers. I suspect it's best to call it a loss if ! & 2 don't work.