I'd reinstall those applications. I hope you kept the install programs on another drive.
But something is strange. Even after formatting space is used for housekeeping purposes. So it shouldn't be 0%. You might need to format it first, if you get a disk error during that install. And it even could be that that fails and you have to repartition it. And if that fails also, just buy a new disk (assuming it's a physical disk, not one of the partitions on drive that contains more than one).
My Files on my F:\ Drive disappeared Suddenly.On that drive i had many softwares Including Tune up Utilities,Daemon Tools Lite,Picasa and Many Other.I Did not even touch the drive for the Couple of days.I Just Re-Booted as Normal and when i checked the drive It was showing 0% Used space.I did not Format either.Here's My PC's Specs-
OS- Windows XP Pro SP3
Anti-Virus - Norton 360 Version 6
RAM - 1.0 GB
A Couple of days ago i even ran a anti-virus scan and No Threats were Found.
The whole Content of the drive has Vanished.
Awaiting YOUR REPLY!!!!