Please Help Me!!!!! My Cat has lost his voice...I think...?

Okay my cat, Sammy, has lost his meow. Whenever he tries to meow he'll open his mouth real wide, but no sound will come out. It just started this morning. We have another cat named Lucy, she still is kitten and she seems fine. Can a cat have a sore throat or any other illness...or did he just lose his voice??? Please answer!!!!!!!!!!