Is life worth living if no one loves or cares for you?

Short answer, Yes!
You still have the capacity to love others! Volunteer your time to organizations that need help. Deliver meals-on-wheels. Tutor a youngster. Join a choir. As you start to spread the love that you have inside of you, you will feel love in return.
And remember...there is always someone that loves you. Even when you don't realize it.

OF COURSE! I can promise you that someone out there does care and love you. I wholly agree with Bill's suggestions as well. Reaching out for others makes you feel better. Life is worth it. There is always someone there.

Of course it is! Even if there is no one right now there is no reason to think no on will ever be there for you. Learn a new hobby and join a community of people who also enjoy said hobby and people will care about you pretty soon!

It's about the love YOU can provide! It's hard because people are so egocentric by nature, but life matters even if you are alone in Antarctica. You'd be amazed the changes you can make in others lives as well as your own. YOU MATTER. We all do.

Absolutely. No matter what you always have potential to do wonderful things. At the very least you can love and care for yourself.

Life is always worth living. Absolutely never give up no matter what, because you are you and no person can topple your resolve unless you allow them to. You must keep strong and carry on, because you still have a life to live and many great things to do with it. Show your detractors you are undeterred.

Yes, and here is my perspective on it.
According to an average person, there would be 2 practical options here. live, or die.
With Life, there's plenty of life to be lived. go skydiving, adopt a pet, do something fun, make friends on blah therapy (PM me if you want to talk to something, I'd like to be your friend!!) fall in love! etc. But basically, there are tons of things to be done. At the end of all of this, death is inevitable.
Now with death, there is much conflict about it on the planet. Is there life after death? Is there a heaven or hell, or do you just sort of float around? And short answer would be; I have no freaking idea. I currently believe in Buddhism, which says reincarnation exists, but I may be wrong. You never really know if you will cease to exist after death. But most important of all, you don't know if you're going to be coming back to earth, and you most definitely won't come back as the current you. You may be a cockroach for all you know, getting squashed and all.
Basically, you know death is inevitable, but you don't know that this life will come back to you the way it is, if it comes back at all. Make the most of your 80 years, then die peacefully!!