If you don’t mind telling us OP, what is your clothing size and height? What about your shape (pear, apple etc?).
We could better suggest some shops, styles or particular garments that may suit you if you answer the above.
Are there any celebrities or family or friends whose style you really like?
Do you like to wear any particular colours, patterns or not?
I also suggest that you have a look online at capsule wardrobes, and get your clothes out and see if you need any of those items. Classic jeans, a leather jacket, white shirt for example are capsule wardrobe items, and can be accessoried in so many ways.
It may be that when you go shopping, that you fall in love with 1 thing, and that sets you on the right track and makes you feel more confident.
You may notice that the quality of a lot of the fibres and fabrics used on the high street has deteriorated, and sizing can really vary - so please try everything on.
As some previous posters have said, a personal shopper may be able to help you. I personally think though that it would be best for you to try and think about what you like and how you want to look first.
Please let us know OP, and we’ll try and help you.