NO, a VPN wouldn't accomplish anything. Just about any firewall will drop the packets coming in during a DDOS against your IP, so no damage would be done to your computer, it isn't a malware attack. The problem comes from the fire hose effect I mentioned, your computer/router wouldn't be able to send anything out to your ISP, whether it's encrypted in a VPN or just web browsing or checking your email, nothing will be able to get out because of the constant bombardment of traffic coming in, which is why it's called a denial of service attack in the first place, you would be denied the ability to use your internet service. It is extremely rare against a home user and would be rather pointless. A dedicated hacker with such an ability would be extremely unlikely to expose his network for the purpose of hitting a home user, the large amount of traffic being generated would make the attacker's network/botnet easily visible and identifiable. This type of incident or attack is usually reserved for large networks or sites.