What is wrong with my Hotpoint Double oven?

I was cooking in my large double oven, a small casserole, which was half through cooking. I was using my PC at the time, and suddenly everything went black. The lights has fused.
I dealt with the fuse problem, but my large oven was only blowing cold air. All the lights were on , the top oven was working.
I scanned my manual, & I was told turn off the cooker & press Manual.which I did .to no avail.
Elizabeth