Having to rely on others is uncomfortable. On the other hand, others will appreciate it when you can be of service to them. Think about what you like to do, what you can do, and do it! Feeling useful helps both you and others. The smallest thing can make a difference.
If someone asks you to do something beyond your ability, you have some choices: politely say no, offer to help do a smaller, more manageable part of the task, or see if you can find someone else who can help. There are a lot of possible choices. These are just a couple of examples to help you get started. Saying no is hard, but its an option. You still might have to look harder for ways that you can feel useful and contribute in a meaningful way to your family, friends, neighbours, and at work.