Hi, it sounds like you are seeking a completely different look to yourself. The only thing vitamins will do is make you feel a bit better physically, you overall appearance comes down to several things
1-lifestyle: general health and condition, this comes through correct nutrition, exercise and hygiene. A good haircut is alway a good start.

2-Your mental well being, your self esteem and how you hold yourself. You may find some courses to help you with presenting yourself as a confident and assertive person. even posture says alot about a person, eg, slouching shoulders generally says that this person may not like themself.so to a potential employer may signal lack of motivation.

(if on the internet you could type in how to improve appearance for esteem etc, there will be good practical advice and baby steps. whe you look good you feel good and tend to be more confident.

3- The clothes you wear, seek some advice on what suits you, the style you are after. what makes you feel good, its doing the research and giving yourself permission to dress up, experiement. This doesnt have to be expensive. As you mature so do your tastes. you are allowed to look good, i would encourage you to be bold. you are worth it.

on the job front i always think, when i have a potential employer interviewing me, what do they see?why would they employ me over someone else. i may not have the most expensive clothing but if i look good, tidy and energetic for the job, then we move onot the important stuff

when you come through that door what do they see, apearance leaves an impression but so does personality.

all the best