Thanks for the reply. I have blown off the mirror and focusing screen and cleaned the eye piece. No dust shows up in the photos. I am pretty sure it's on the inside of viewfinder. And after cleanning everything nothing changed.?
If the dust is in sharp focus, then it is likely on the focusing screen. However, blowing off the bottom of the screen won't remove any dust that's on top of the screen. Screen removal would be required. Not sure if that can easily be done on the D3000 or not.
There is a retaining spring that could be removed, and under the focusing screen is a shim. Once you get the screen and shim out, you could try blowing out the dust or blow it from the focusing screen. Now you have to reinsert the shim and focusing screen and reset the retaining clip. You will also need to make sure you orientate the focusing screen correctly. There are 4 different ways to insert the screen and only one will be correct.
You could scratch the focusing screen, or add additional contamination unless you have the correct tools and an know how to use them in such a manner that you do not damage the parts. The shims for focusing screens are very thin and fragile.
You might consider a camera repair service or just live with it.
You would be surprised at how much dust can get inside a lens and not affect the results. Unless the dust is affecting focus or exposure, I would ignore it.
Edited to add:
Unlike many of the Nikon SLR cameras, the focusing screens in dSLRs are not designed to be easily changed. They are not in carrine frames like the SLR screens are. They are also fragile and easily scratched,