Writing a letter to your hostel manager to defend yourself on being accused of accommodating an opposite sex in yoir room

Yes, you probably could. Or you can find another place to stay. Really not much you can do....you are only a guest there.

Are you looking for help writing the letter, or asking someone to write it for you?

Bottom line, you'll have to prove that you didn't do what he's accussing you of. Can you prove it? If not, the hostel manager can kick you out if he/she thinks you broke the rules. It's sadly not up to him to prove you're guilty, it's up to you to prove you're not.