>I cannot access all files (icon) in control panel.
Try repairing with TweakUI (http://duxcw.com/faq/win/icons.htm), etc.
>can we convert exe file to doc file using regedit or msdos. You can’t convert them, but you can rename them with MS-DOS, but windows would be easier, as follows.
You can change a file from name.exe to file.doc by right clicking it with the mouse, selecting rename, and editing the name. Or, click the name once, wait a little (so Windows doesn’t “think” it’s a double-click), click it again, and edit the name directly. Or, select the file and click File main menu and select Rename. Or, select the file and hold the Alt key whil pressing the F followed by the M keys.
This is a very odd problem and I suspect a virus or human error.