Correct (22): I read a newspaper article about a disabled man who had managed to achieve great things and help others.
Explanation: In the original sentence, "man had managed" is incomplete. We need the relative pronoun who to connect the noun with the clause describing what he had done. Without "who," the sentence is grammatically incorrect.

Correct (23): I realised why God had made us like this to give hope to others.
Explanation: The original used has made (present perfect), but the sentence describes an action that happened earlier than Nick's realisation, so we should use the past perfect had made. This shows that God’s action occurred before Nick’s realisation.

Correct (24): It was so inspirational for me that I decided to use my life to encourage other people and give them the courage that the article had given me.
Explanation: The original used inspiration (a noun), but here an adjective is required to describe the feeling. The correct adjective is inspirational. Also, for me is more natural than to me in this context.

Correct (25): I decided to be thankful for what I do have, not get angry about what I don’t.
Explanation: After decided to we need a verb in its base form. Since thankful is an adjective, we must use be thankful to make the phrase grammatical.

Correct (26): I wanted to concentrate on something good that I had.
Explanation: After wanted we use to + verb, so the original wanted concentrate is missing to. The correct form is wanted to concentrate.