If you mean the Canon 7D Mark II, you need Lightroom 5.7 or later.
If you mean the original Canon 7D, then you probably have corrupted files.
What DJ said.
I own both 7Ds, and they work just fine in Lr 5.7.x.
Which "other programs" do your files open in? Are they Raw converters? Many image viewers only open the embedded jpeg preview in a CR2, which can often be accessed even if the Raw data are damaged.
Thank you. It is the Mark II. I will try to upgrade Lightroom to 5.7