Dear, dear LonelyGirl1957.
I relate to what you are experiencing, and it took me quite a time before I learned what to do to make things change. As those who have already answered with their suggestions, I have learned to be comfortable within myself. Being alone doesn't have to mean being lonely. Learn gratitude for everything that you are, have, can do. Learn to love yourself. How? Do those special avtivities/things that you really enjoy -- a walk in beartiful nature, a long sented, bubble bath, doing a special method of exercise, maybe swimming, biking, tennis, gardening. (It helps your system release dopimane - the feel happy, natural hormone. How about listening to music you love, dancing to it -- alone, but not lonely!
Listen (carefully) to the innter talk. Is it critical, demeaning or nagative? Tell yourself "No, that is not what you'll acept and replace it with a positive affirmation -- I am happy with who I am and I daily work at changes which makes life easier. (Or whatever feels right to you as a positive statement.) Louise Hay has books, which might help in this area, and has a column in which she answers questions.
Watch what you eat, if there are food allergies, they can cause negative feelings. Be sure to eat a healthy diet.
Sleep -- are you getting sufficient rest? That can make a difference.
Water, be sure to stay well hydrated.
Can you join a group who are into some hobby, interest, or activity that you like?
How about a spiritual or religious group? People with like interests.
Meditation -- very helpful to find answers to what you are looking for. It is uplifting, calming.
There is a site which has helped me a great deal, if you care to google it, you will find it -- First30Days|Change Positively.
Much love and light to you, dear friend