First, let's review the question:
Hey Subha, did you post photos on Facebook last night?
This is ok. But at the same time, it doesn't sound quite right. The following would be preferable:
Hey Subha, did you post any photos on Facebook last night?
Unless the question really was about only one photo (a more specific case) and then it could be
Hey Subha, did you post a photo on Facebook last night?
Next, going on to the response:
Me: No, I didn't post (any)photos but posted a status.
The reply follows the same pattern as the question, it would sound most natural with either "any photos", or if it was really focused on one for some reason, then "a photo".
And finally, it would be preferable to say "... I posted a status." You had omitted the "I".
Ignoring everything which has been said here, the original sentences are still quite understandable.