Good pictures of any markings would help, but it looks like a European parlor pistol, probably made for a 4mm or 6mm cartridge with only the primer for a charge. The bad news is that those were made in large quantities and unless they are very fancy are not very valuable. If in good condition and functional, they usually bring around $50-100 retail.
Others may be able to offer more or better info, but that will depend on better pictures and description.
Jim