I think my tree is dying how to save it?

Hello I bought a bonsai tree I bought it half a year ago for 2 and a half months it lived fine but didn't grow I assumed it reached its maximum size and then it suddenly started to be kind of brown like in the picture I don't know what kind of tree it is does anyone know what the problem is and how to treat it?
*And if anyone recognizes the type of tree, I would appreciate the name of its variety

No pictures attached.