I think that it will be more easy than reinstall The OS.(of course a small search on the forum would help you a bit and had saved you a lot of time ;) )
Go to ...\HearthRanger\task folder and open "HearthRanger - Bot for Hearthstone.tsk" file using notepad.
Search for "<sGamePath>" string. When you find it, put the path for hearthstone.exe there.
Example:
<sGamePath>
C:\Hearthstone\Hearthstone.exe</sGamePath> <--.Put here your path
Save it and try.