Why is my stove is no longer receiving 240V of power?
Like Ecnerwal says, you lost a phase.  99% of the time this is the power company's problem, and they come out and fix it for free.  Simply report an outage.
But why aren't half my circuits dead?
Because the two phases are shorted together.
OK it's not a dead-short, it's a low-resistance short.  If the power were working normally, this thing would be making an awful lot of heat.  But it hasn't burned the house down, so the heat must go somewhere non-destructive.  Where could that be?

Oh, hello.
Yup. All the 120V loads on the dead phase are being supplied from the other phase through the water heater's heating element.
Some time after you lost the phase, the element in the water heater cycled on for normal re-heat, and it didn't work normally because of the lost leg.  However, being in series with your small 120V loads such as lighting, cable box and the like... the big resistor made some heat.  Water heaters are stupendously well-insulated, so running through the whole day, this small amount of heat was enough to re-warm the water in the tank, masking the most obvious symptom: total loss of hot water.
But I don't have any 240V appliances that could do that.
Your neighbor does.  And you're both on the same side of the wire break.
Call the power company and report an outage. Unless your area just had an ice storm, you'll be at the top of the dispatch list and they'll be out in an hour or two.  20 minutes on the poletop fiddling with connections and you'll be right as rain.
Now, if you want this to go faster, be within shouting distance while the worker is up in the bucket. Be the &quot;gofer&quot; to alert neighbors and shut off main breakers so the worker doesn't have to come down.  They ought to send 2 people, but, y'know.