Is my oven dead? ?

This is an Ignis single built-in oven I assume? With the very basic information provided, I'll also assume that your oven has been functioning perfectly until now, there has been no loss of performance recently and the control knobs feel the same as they always have when you turn them.
If the display is still lit up, check you have not accidentially selected a timer mode where the oven can switch itself on and off automatically. Instruction manual will describe this function and how to reset or exit this mode and return to normal.
If the display and clock is not showing, then you need to investigate the power supply. First, there should be a separate switch on the wall to isolate the oven power, check this is on. It may be in the back of a cupboard and an item in the cupboard could have been pressed against the switch and turned it off.
If the oven installation has been bodged, the oven maybe simply be connected to a socket behind the oven and this plug and socket could have overheated slightly causing a bad connection. Locate the cable coming out of the back of the oven to see where and how it is connected. You will need to remove the two screws in the left and right side front lips of the oven (visible when the door is open) so it can be pulled forwardout of the kitchen cabinet. You will need someone to help you do this.
Once the oven is out, and you find it is plugged into a socket, unplug it and try plugging into one of the wall sockets above the worktop and see if the oven powers up. if not change the plug, put in a new 13amp fuse and try again.
Also check your main fuse box to see if one of the breakers has tripped.
If the oven works on this alternative socket you will need to replace the faulty wall socket behind the oven, also if the oven has no plug and is wired into a plate in the wall and not a socket, you will need to have the wiring checked by an electrician.

Rupert
December 2019