what does this mean?

"kangaete oku nai yo ne?"

Kentatsu,

"kangaete oku nai yo ne?"

Context would help tremendously, but I imagine it is supposed to be two separate phrases: "Kangaete oku. Nai yo ne?".
The first phrase means "I'll think it over." The second part can mean something like "You don't have any?" or "There isn't any?" depending on context. Post more details if you want a more accurate answer.

kangaete oku nai yo ne?

...is not a correct sentence in Japanese, so, yes, context would help to find out exactly what it was *supposed* to be.

Maybe it was "Kangaete oku. Nai yo ne?" as suggested already. Or maybe it was "Kangaete okanai yo ne?" (You are not going to think it over, right?)," though a bit unnatural, or even "Kangate, yokunai yo ne? (Think about it, it's not good, right?)." Or even "Kangaeru hoka nai yo ne? (There is no other choice but to think about it, right?)." So... yes, context would help tremendously.