Having been a landlord I share my experience with how to take action. This is not legal advice since I am not an attorney.
Have you read your contract to see what it says? It could be disclosed in the contract. If it doesn't say anything about the lack of an oven, then I would definitely talk to the owner. Explain to them that this is essential to you and that this was not disclosed to you prior to your signing the rental agreement. Then listen carefully to what they say. Let them do all the talking so that you can see whether they will accomodate your request. From my experience, it is best to be non-confrontational about this, just factual. You do not want to say anything about further action, because frankly every situation is different and you don't know if you are entitled to one based on your contract or the law. Perhaps your unit can't accomodate one. So be nice.
After that, you will know whether you need to take any further action. If they agree, then there is no further action that needs to be taken. And I would thank them. If they do not agree, then you can seek the advice of an expert in Landlord/Tenant relations (attorney, your City, etc) to find out if there is any more action that can be taken. Best wishes.
Remember, this is NOT legal advice, this is based on my experience.
Best of luck,
Coldwell Banker Star Realty
BRE Lic #01456982