Replying to Serious SD Card Issue, Really Need Help

Today I took my SD card out of my Canon HSF100 camera to film on my friends T3i, and I went to look at all the footage on my computer and cannot find the footage at all. I have absolutely no idea where the footage went, and can't find it on my SD card. I know for sure I was filming and it recorded, as we watched it all back on the camera after the day, but I can't find it on my computer, and can't import it to Premiere Pro to edit because I can't find it....