Shyness isn't a lifelong personality trait. Learning to talk to strangers is a skill you can acquire. Want to know how Conan O'Brien and Will Ferrell got over their shyness? Using a technique called "radical implosion". Radical implosion is based on psychologist Albert Ellis's shame-attacking exercise. The idea is to do something much more intimidating than whatever you're afraid of. Once you get over that, your original problem seems easy, and the anxiety around it more manageable.
For example, Conan O'Brien started performing live comedy because that's what frightened him most. To over his shyness, Will Ferrell would purposely do idiotic things in public, so people would laugh at him.
While their examples are extreme, the core idea is solid. If you're afraid of talking to people at a party, go and talk to 50 strangers in a park first. Just see what happens. The party will probably be much easier.