I would suggest that you do a search for helpctr.exe on your computer (go to Start then Search). I found two of them. The one that Windows uses seems to be in C:\Windows\pchealth\helpctr\binaries
You might try Microsoft. Try their knowledge base. or try tech support via E-Mail. While you can often find *.dll type files on other sites, the file you are looking for is part of Microsoft's program.