I use WiFi on home and on CyanogenMod 12.1 so I use chrome browser latest update on it. So when I am downloading file but for some reason I have to go outside , as the moment I disconnects from network download stops. Any solution to prevent this thing? I tried That part download thing in download folder but its not working either.
Well, you need some kind of internet connection to download files. From what you said, the download stops when you disconnect from your network.
If you meant that the download doesn't work over mobile data, check the list of apps with restricted background data access for Download Manager or, of course, Chrome. If one of those apps have restricted background data, disable that option. If it still doesn't work, try a different browser and tell me whether that worked.