If it allows you to, try running chkdsk on the drive. Open a command prompt window and run chkdsk. (click start, program, accessories, command prompt, then type in chkdsk x: where x is the letter of the drive.) If it reports a couple of errors, try running chkdsk /f (that’s the fix flag). it’ll try to repair the errors. If there are any consistencies in the file system it’ll fix them (these can happen when the drive powers off in the middle of a write for example). If the file seems gone after running chkdsk /f, look around for a folder (it may be hidden - so go to folder options and allow viewing of hidden files and folders) named found.000. It will have files named .chk. Just rename them to the extension of normal videos and they should play fine.
Next step up is to try file recovery software. Just google for data recovery software.
If you hear any odds sounds from the drive like clicking, don’t run chkdsk or any software recovery programs. It may indicate a hardware failure and any attempt to read or write can only cause more damage. (hard drives are very sensitive to shocks and bumps, even slight ones - I never could understand why people thought it’d be cool to include them on portable devices.) If the camcorder is still under warranty you could get a replacement for it (though I don’t think they’ll get you your video back). If you need the videos back at any cost you could turn to a data recovery company (but they cost an arm and a leg).
I have a JVC HDD internal harddrive camcorder. When I am dragging and dropping to copy movie files from the camcorder to my desktop, all of a sudden it will stop in the middle of a group of movie files and give me a message that says (file name) cannot be copied. Parameter Incorrect. So, I am stuck with these files on the camcorder hard drive and unable to get them copied to my computer to burn them to a DVD. Some files will copy and some will do this Paramater Incorrect thing. I have spent hundreds of dollars on this camcorder and its useless with my movies stuck on it. And some won’t play back on it saying HDD error