Laptop is full but I have nothing saved on it.?

When I say full, I mean it's in the red and giving me pop ups to warn me that it's critically full. I have no videos, movies pictures, music or video like files at all. My husband has loaded some programs for work but that was two Months ago and it wasn't in the red after he had installed them. He's obviously away for work now and I'm not able to can't act him for another three days. Is it some sort of virus or something? What can I safely delete without taking something off that will affect how it runs? Where do I even start? I plant vegetables and raise kids, seriously no tech knowledge at all! But it'll crash unless I do something soon. I also don't live in an area that has access to tech shops, we're quite isolated. But I really need my email to keep in touch with family. Help