Use the Avast Uninstaller. Be sure to select the proper version your trying to uninstall from the drop down menu. Also make sure your point the uninstaller to the director of the installation which is usually C:/Program Files/Avast.
Reboot
Run Avast Cleanup Tool.
Reboot.
Install a fresh copy of Avast
Be sure you do nit have any 3rd party firewall which could be blocking Avast’s updater. The only other thing is that a malware infection can stop your antivirus from updating.
OK, try the avast repair for a first step if that doesn’t work then a clean install.
Try a repair of avast:
Win7 - Control Panel, Programs & Features, uninstall a program, select ‘avast! Anti-Virus,’ click the Change/Remove button and select Repair, click next and follow.
You may need to reboot after the repair.
This has in the past resolved this out of sync issue between reported and actual VPS version.