How to lighten the darker parts of image

As Photoshop users gain expertise, they largely end up using 'Levels' or even better (in some cases) perhaps 'Curves' Adjustment Layers. 

Save the layered file, copy, flatten and work on the copy to send. That way you'll have the option to go back to the layered original and carry out non-destructive edits [flattening an image with adjustment layers bakes in the adjustments] 

I hope this helps
neil barstow, colourmanagement net :: adobe forum volunteer:: co-author: 'getting colour right'
google me "neil barstow colourmanagement" for lots of free articles on colour management

https://m.youtube.com/watch?v=meFr1mKkWqM

Unfortunately i just couldn't make the image go well in the poster.

Thank you for all the replies anyway, i learnt alot.

Yes i assume the image was taken by students with what they had to work with [hardlight is great for buggering colours] but yes if the book is still available or better yet you know a skilled 3D artist then remaking the image will give the best results

My two cents worth;

The Camera Raw filter is a one stop shop for fixing all sort of exposure related issues, and it does it so well.  You would make the layer a Smart Object to work non destructively — I often find I change my mind a wee bit down the road, so it is nice to have the option to fine tune, and why the heck wouldn't you?  It's a no brainer if ever there was one.

A question:  Is Image > Adjust > Shadows / Highlights the same as the same tools in Camera Raw, or is it the original version, because that was pretty nasty, and could leave you with blocky 'bad HDR' like results.  I have never used it, but did just try it and I think it must use the current Camera Raw algorithm, because it seemed to work OK.

When you need to get heavy handed with curves and levels, it can affect the colour, and I don't think anyone has mentioned the trick of setting such a curves adjustment layer to Luminosity (or using Edit > Fade if applying curves directly) to minimise the color problem.

Oh My Ged!  I am doing the unthinkable and talking about colour problems, which is something I usually try to avoid and leave to Dag, so I think I'd better better get ahead of any flack, and use my own post signature line 😉

Author of ‘Self Promotion as a Substitute for Low Self Esteem’

its dark because the photo is over exposed so imo hue adjustment is the wrong way to go i.e, there is already TOO much light washing out the detail

How do i lighten the shadows or change its colour?

By @Summayah5FC7

You can lighten shadows using Curves for example. To change color of black use Hue Saturation, turn on Colorize and play with Lightness in positive up to 50, Saturation and Hue sliders as shown below on screenshot. It may or may not work for you but I think it is easy enough. You can, for example, mask book to exclude it from colorization.

You can use the Shadow/Highlight feature in the Image>Adjustments>Shadow/Highlight - but that will permanently change your pixels (it's what we call "destructive" editing). If you use that option, I strongly suggest using it on a duplicate layer - or a stamped layer.
But, One of the strongest ways to do this is using a Curves adjustment layer. (https://helpx.adobe.com/photoshop/using/curves-adjustment.html)

The nice thing about this way, is you can use your layer mask to adjust where the adjustment will affect your image. And, an easy way to create that layer mask is to use the Select>Color Range option. 

Hope this video helps.