User accounts were deleted

A client has a peer to peer network with Windows 2K pro workstations and a Windows 98SE.
On one Windows 2K pro workstation, a number of accounts along with associated files were deleted by accident.

Now the MS Office 2000 Pro is not working even though Winword.exe, Excel.exe and other files are under “Program Files/Microsoft Office/Office”.
When Winword.exe is double clicked, an error message pops up.
Reinstalling MS Office Pro has failed with error message.
I will post more with detailed error messages.

In the mean time, any idea what might have happened and how to make the MS office work?
Any idea how to retrieve Outlook e-mail messages of a particular account assuming deleted files could be retrieved?