Canon Powershot Sd1200 Is
How I can make the sound audible in my Canon Powershot SD1200 IS?

When you take the video, and play, no one can hear the sound at all. Is there any way to fix this? I mean, I used to have sound … I'm just looking to upload videos on YouTube, so little needs to sound.

Read the manual / user guide: http://www.usa.canon.com/consumer/controller?act=ModelInfoAct&tabact=DownloadDetailTabAct&fcategoryid=323&modelid=18144 page 47. Has the playback volume of the camera is really muted or low? When the video was recorded, was something that covers the hole in the microphone? See page 30 in the User's Guide.