I lost my sound on my vhs video player?

i was playing a video in my Panasonic NV FJ 620 and then i lost the sound after i look in side the player to see what was wrong i saw that the sticker came off the video cette, so i open the unit and took it out but when i put the unit back together i still haven't got any sound what can i do, it a good player and it never chew any tapes;