How to fix broken context sensitive help in IDE of Delphi 2010

Question

After working for quite some time, my D2010 help system broke.

Highlighting a keyword like TStringList and hitting F1 results in the message \"No help found for con

Answer 1

The methods of using h2reg.exe did not work for my case (RAD Studio XE3). It costs me several hours to find out my solution. The root cause of my problem is the broken Microsoft Document Explorer 2008. I try to repair it from Control Panel -> Uninstall Application. Surely you can remove it and install it back from many source, including the help system of RAD studio.

Try this if other ways don't work.