Maybe. Unplug the toaster and remove the bottom plate as you would for cleaning. look for the wires connected to the middle elements and see if one has become disconnected or broken. If one or more of the connections to the middle element is a quick disconnect type (click link for a picture),
then inspect it for overheating, oxidation or corrosion. You may be able to clean it up with a Scotch-brite metal polishing pad.
On my toaster, the connections to the heater elements are metal strips riveted to tabs from the element assemblies. One strip is riveted to the power neutral; the other has a quick disconnect tab for a wire from the thermostat. A loose or broken rivet could be the problem, but do not use an aluminum pop rivet to repair it. It can't take the heat, even if you could find one small enough.
I've seen toaster heater elements evaporate over the years - they get a hot spot, which burns off metal, making it thinner and hotter until finally there's nothing left there. At that point the element is gone. I suppose if you could find nichrome ribbon wire of the same width and thickness as the original, you could rebuild the heating element plate, but it would be a delicate task because the mica insulating material is fragile. It's probably more practical to scavenge a working heater assembly from another toaster of similar design, if the electrical connections are serviceable with the tools you have.
Unless this is a very fancy unit, it's probably cheaper and easier to scrap it out and replace the whole thing.