I totally understand your situation and how you feel. Here is what I've learned:
Learn to love yourself.
Sounds cliche, I know. But if you don't love yourself, then no one else will either.
Be loving and you will be lovable.
Quotes can explain it better than I can. "Only by loving does love come to us. The more we love, the more love comes to us.” “Love is never outside ourselves; love is within us.”
Be open to receiving love.
You need to be open to receiving love. How do you do that? You must first acknowledge the love you have in your life--this opens you up to receiving even more.
Let go of wanting love.
I learned this from the Release Technique and it works very well. Wanting is a distinct feeling or sensation of not having. When you want something—like love—you experience the agony of not having love. Wanting holds in mind lack—in this case, a lack of love. If you are holding in mind lack, then that’s what you are going to get. The Release Technique has some excellent exercises to help you to let go.