The theme is quite empty after installing

So, i recently bought the theme and installed it after the purchase.
I really loved the demo but when i look at my site its just.. empty.

I wanted to install the demo files, but it says i need to reinstall wordpress, what i dont want. because i already installed a lot of plugins and dont want to lose them all again.
It was plenty of work…
Is there any other way?

Help. 🙁