Everyone is worthy of love. Being ready for it/a relationship is another thing.
My answer is like what the guy above me suggests. I worked on myself.
Worked to identify what my assets are, and what I like/value about myself. I identified my faults and thoughts of ways to either correct them or to accept them as part of me. I've worked to take responsibility for my past missteps and tried to not only not repeat them, but to do better. I worked at trying to be a nicer and kinder person in general. I've tried to be more impeccable with my words, be more empathetic, speak up for myself, let go of things that are not for me. Just trying to be a better person and someone that if I met I would want to get to know.
It's not that I never feel worthless anymore, or am doing all things perfectly now; but the observation of progress and the gaining of assets in the process has raised my self value and confidence. If you want to feel worthwhile you have to start with you.
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"Inside the heart of each and every one of us there is a longing to be understood by someone who really cares. When a person is understood, he or she can put up with almost anything in the world."