After reset i updated my iphone to latest iOS from that time i am unable to see my old pics which were uploaded to my photostream. That is the main problem
So you are seeing My Photo Stream but not the older photos in My Photo Stream?
If you updated your iPhone and restored it from a back the Photo Stream will only show newer photos. The backup does not include the Photo Stream. So the Photo Stream will have to be restored from iCloud. And iCloud will not store your complete Photo Stream history. It only keeps the last month of photos, and your iPhone will only download up to 1000 photos. Your devices may keep more photos in the local copy of the stream, but when you restart the photo stream, you will only get what is currently in iCloud.
If you sign out of iCloud or turn off My Photo Stream on your iPhone, iPad, or iPod touch, all of the photos in the My Photo Stream album are removed from that device. Any photos from My Photo Stream that you imported to the All Photos album and the Photos tab are also removed.
The photos from My Photo Stream on your other devices aren't affected. Photos from My Photo Stream will stay on the iCloud server for 30 days from the date you upload them to My Photo Stream. If you sign in to iCloud with the same Apple ID and turn on My Photo Stream on another device, the photos will automatically download.
Before turning off My Photo Stream, you should save any photos that you'd like to keep to your device. Learn more about saving your photos.