I have a whirlpool oven which I bought from Ikea a few years ago but at the end of a timed programme the beeper is not going off can you tell me the answer please.

many stoves have what is called SABBATH mode and if so you need to tell it that it is not Sunday i personally would call a repair service

Unplug or isolate the electric before doing anything.
Check if you need to take the oven out or if you can remove the heating element by unscrewing a few nuts and bolts from within the oven itself .
Elements cost about £10 - £15 in the UK and are available from Ebay or Electrical Parts wholesalers or alternatively from the company itself if you can find a manufacturer , The name shown on the product may just be a Logo brand name but manufactured by a larger company for a specific store.

No way to tell until you take the whole thing apart.

Hello, Thank You for using FixYa. I will be helping you today.I would recommend paying for a service call to have a tech take the door apart for you. There are four pieces of glass in the door and lots of screws. It really is a pain to take doors apart we as techs get this call all the time. Believe me you will thank me you paid someone to do it. If it were easy i would tell you. Most people take them apart then end up paying because they cant put it back together.
Thank You and please rate my answer if it was helpful..

No solution, just that you are not alone. We have had our Whirlpool super capacity 465 for 10 years, and about a year ago that large burner started to randomly go to high, even though the control is set to simmer. Ruined a few meals by not being right there watching.

Its not always the oven temperature sensor.
can also be a bad circuitboard.
or config figuration.
there is a on youtube someone how to do it.
i had a 20 year old oven with de failcode F 03.
fixt it with the config and it works again.

After a powerbrake the IKEA Whirlpooloven doesn´t work, the display just says STOP and nothing works, not even the light inside the oven. This always happens after a powerbrake and usually I can fix it after some time pressing different buttons but not today. Suggestions?

I would go to a Lawyer unless you have a serious voltage problem. Whirlpool makes pretty good appliances. To have probems with all of them is very unusual. Look for a comon problem. You have not stated your outher problems. I have heard about oven glass breaking with no reason.

Hold down the 'ok' button and it should be fairly self-explanatory from there.