Not clear whether you downloaded from HERE ... To download, you need to log-in using the SAME credentials that you use on this Forum. Download on your PC then connect the phone to PC and Double click on the Installer. Nokia Suite will be launched automatically and then follow instructions...
Hopefully, you have Nokia Suite installed on PC...If not download from HERE ...
You may use the link provided in the earlier post thru' your Phone Browser..Log-in using the SAME credentials that you use on this Forum..and search for Store Client for S40 ...Once the installer is downloaded on to your phone..click on it to install ...
Have you tried option to re-install existing device software using Nokia Suite upon your PC?
Symbian specialist until 31/01/2013 with interests in Maemo & MeeGo but an aversion to Windows!