If you can, go to your local public library and have a chat to the librarians. They are a goldmine of quality recommendations.

For horror, Stephen King is one of the best. Start with something shorter of his, a short novel, or one of his collections of short stories. His longer novels are great too, but his short stories are where he really shines.

A couple of my favourites are:

1408

The man in the black suit

Pet Cemetery

The raft.

The cycle of the werewolf.

Happy reading!

Edit: for mystery I enjoyed Six Wakes by Muir Lafferty, a SciFi murder mystery on a spaceship. I also enjoyed Agatha Christie's Hercule Poirot stories, they're fairly simple and easy to read.

My favorite recent book is Piranesi, by Susanna Clarke! It's a mystery/fantasy with light horror elements, and thoroughly stole my heart. I also recommend checking Standard Ebooks for high quality, free, public domain books! If you have some money, an eReader can really help you save money in the long run, or you can read on your phone using book apps like KoReader!

How old are you then?

Don't know if it's your taste, but my most recent favorite is The Dispossessed which is a political sci-fi kind of book about a brilliant mathematician who lives in an anarchist world

i really enjoy horror/mystery!

Might I recommend 14 by Peter Clines. It should scratch that itch.

The Silent Patient is another good mystery one.

Dracula is my go to. There is a daily email you can sign up for that follows the books entries. Jurassic Park is good as well.

Maybe try The Fisherman by John Langan. https://en.wikipedia.org/wiki/The_Fisherman_(novel)

I usually read sci Fi stuff but that was a good horror mysterious one.

Good for you, I'm glad you've gotten into it. However this statement is kinda confusing me. Did you not read before because you didn't like the genres available to you? Is it a new language thing? Are you young?

Dan Simmons. Summer of Night. Give it a try.

Personally, when I was new to reading, I liked the DK Books reference books for their pictures, and also enjoyed the Hank The Cowdog series. For mystery, I'll recommend Encyclopedia Brown, because it actually requires reader participation.

As far as horror goes, I'd recommend The Hellbound Heart, because Clive Barker is a genius when it comes to suburban horror, and exposing the sinister desires that fester in the hearts of the repressed.

None of these statements was false, but only one of the recommendations was genuine; I'll let you guess which.