Hello, Ashik, and welcome to the Grammar Exchange.
I agree with Ahmed that "I do like gardening" is more emphatic than "I like gardening." The sentence with "do like" would also take a special context.
Normally, to be emphatic, we would add "really" or "very much": "I really/very much like gardening." We'd use "do like" to, for example, make a correction:
A: I thought you didn't like gardening.
B: No. I do like gardening.
I invite you to review our Guidelines page, Ashik. It will teach you how to decide upon a proper title for a thread. "Need help" is not a grammar topic.