missbeba, tell us more, please.
It is hard to guess, what might be wrong without more information.
First of all, what is your Aperture version and what is your MacOS X version?
my photos show that master image is not available
Where does Aperture expect your photos to be? You can see that, when you select one of the photos with the missing master/original and use the command "File > Locate Referenced Files".
This will open a panel, with the versions with missing master in the upper part, and to the right is a thumbnail of the selected image. Below the thumbnail is the file path the original file. What does it say? Are your missing photos still in that location?