Grey and White are neutral colors. It is because they're neutral colors that virtually any color can be made to coordinate with your furniture. You can try a stark contrast with black of compliment it with a muted shade of White, Brown, or Gray. You can also try different bold colors like Red, Blue, or Green to add excitement.
For Walls
Contrasting/Vibrant: Reds like a cinnamon, terra cotta, or brick.
Calm/Cool: Blues like cloud, ocean, periwinkle, or cornflower.
Warm/Neutral: Peach, mauve, or mustard.
For Curtains
Ivory, bone, cream, or beige.
You should most probably paint your wall a nice beige color. And for the curtain color, you should get a white crushed satin look. It will bring the room together well.