I don't thing a manual program update will do the job and over come what you have done to cripple avast, you really need to start from scratch.
Why did you remove all of the registry entries, what was your purpose?
Are you running another AV?
If you are running another AV, then there is little point in installing a second resident AV as this is likely to cause conflict.
Download the latest full version of avast from the web site and save it to your HDD, also download the Avast Uninstall Utility,
find it hereThe reason for the uninstall tool, you may well have stuffed up the windows add remove programs, which you should first try if that doesn't work then run the uninstall tool.
Having uninstalled avast, reboot and install using the latest version you downloaded and reboot.