my render is taking 12 hrs for 1 frame in cycles 800 samples ???
whats wrong or what can i do to speed it up???
There is zero useful information in your post. How do you imagine we are supposed to come up with an answer?
What are the rest of your render settings? How complex is your scene? What material settings are you using? What’s your lighting like? Post your .blend file to www.pasteall.org and share the link. Don’t make us guess.
Also, what are your system settings and are you using gpu or cpu, etc.