no one knows, there could be many reasons, contact them and ask.

but where to contact. No contact details of adwords??

have you tried using the contact link or running a google search for their phone number?

Yu don't say whether or not it's on the Content network. If it is, my understanding is that if the price you're offering to pay is greater, the respanse may be faster!

ok. yup its on content network also.

you could try and call google or email them but likely you will get a cookie cutter answer that doesn't help you. Do you use adwords editor? sometimes if you reupload your campaign using adwords editor it gets approved quicker. What niche is it...if its a health niche it takes a while to get approved sometimes..

It is educational niche

It sounds like you are new to Adwords. It can take a week for new accounts.

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Just wait.
However, that looks strange. It tooks me only a couple of hours or minutes for a new campaign. Please check all the terms used in your ads.