I am reviewing the schedule our contractor did and it has a baseline duration column, which shows durations. Then I wanted to see the baseline start and finish dates and inserted those columns but it says n/a in those columns for all activities. how is it possible that the activities in his schedule have baseline durations but not baseline start and finish dates?

I checked the set baseline option and it doesnt say anything when baseline was saved so it means he didnt save basline correct? so then baseline start and finish dates showing n/a makes sense however why is there duration values for baseline durations then?

It sounds as though he may have just copied and pasted the duration to the baseline duration. When a baseline is saved automatically saved are:
Baseline Start
Baseline Finish
Baseline Duration
Baseline Cost
Baseline Work