Looks a lot like this $20 mount on Amazon. Hoping this amazon link doesn't get flagged. not sure if it's the same but you're missing almost half of it so you're buying a new one either way.

PERLESMITH Full Motion TV Wall Mount Bracket for 13-42 Inch Flat Curved TVs Monitors up to 77lbs Max VESA 200x200mm- Articulating Arms Swivel Tilt Extends Rotation- PSSFK1