Update

You've skipped a lot of updates. If you are trying to update over the air and it's not working, try updating your phone using your computer with iTunes. This link will guide you --> Update software on iPhone, iPad or iPod touch in iTunes on PC - Apple Support

See if you can borrow a computer from a friend or relative. If not, then I suggest you pay a visit to your local Apple Store or Apple Authorized Service Provider to have them take a look. They should be able to get this sorted out for you.

Which exact iPhone model do you have? What version of iOS is it running now ... and what version are you trying to update/upgrade it to?

What model iPhone do you own and what is the current iOS version on your phone?

... and you want to update it to iOS 14? If so, what exactly happens when you try? Do you see any error messages? Are you trying to upgrade "over the air" or with your iPhone connected to a computer?

Have a friend with a computer? If all else fails, go to your Apple Store where they can help you update your phone.