If the hotspot shield folder is still intact,the uninstaller may still be present there.
Should be located,(depending on your operating system and whether you're using 64 or 32 bit) at one of these locations:
C:\Program Files (x86)\Hotspot Shield
or
C:\Program Files\Hotspot Shield
If the folder is still present,look for Uninstall.exe located there,doubleclick it and see if any remnants of hotspot shield will uninstall.If that's successful,try reinstalling it again and see if works.