How can the problem of lack of self-confidence and fear of people be solved, especially the fear of coworkers, and the feeling of dread from sudden noises or the sudden appearance of things and people, by seeking help from the Qur’an and Sunnah?

Fear is of two types: an innate type, which is permissible, and a type that contradicts faith, such as fearing for one's sustenance or lifespan, which the Shari'ah has forbidden. To overcome fear, one should strengthen their faith in Allah, increase their trust in Him, frequently remember Him, rely upon Him, and know that what was destined to befall a person could not have missed him, and what was destined to miss him could not have befallen him. Allah the Almighty says: (Unquestionably, by the remembrance of Allah hearts are assured) and (And whoever believes in Allah - He will guide his heart) and (And whoever relies upon Allah - then He is sufficient for him).