Hi,
so today I brought out my oboe to study like I do almost everyday and when I went to blow into it NOTHING wanted to come out. I have studied for 2 hours yesterday and I haven't had any problems, I tried million reeds to make sure the problem aren't the reeds and I also cleaned the octave holes and cleaned the instrument inside out just in case it had any water in it. It is really frustrating me now and it has never happened to me before! Can anyone give me any help what can I try to do please?
Thanks.

It might help to soak the reeds. Also, check that the oboe has no cracks or missing pads. Also, when I have that problem, I just pinch the tip of the reed and blow warm air into it (not trying to make any noise). After that, I let it sit and use more air to let it play.

Something in the top joint went awry. The suction in the top joint must be at least thirty seconds. Check the pad suction on all the pads in top joint with cigarette paper (make sure the pull on each of the pads is good enough). Also, the posts of the oboe may have shrunk if the oboe is wood. Then in which you will need to bring the oboe to a repairman and have him end-ream the key. Either way, I would just bring it to your repairman. You said you removed the octave vents?