What happens to the artificial satellites after they stop working

Also hubble telescope is going to retire soon. What nasa gonna do to it?

Once they use all their reserve fuel, they eventually fall out of orbit because of friction with upper layers of the atmosphere, which has a variable elevation. Most of them burn up completely during re-entry, but a few large chunks may survive long enough to impact the surface, usually in the ocean. Don't worry. The military people in Cheyenne Mountain are keeping track of it.

If CONGRESS gets off it's figurative butt or gets elected out of office, Hubble is supposed to be re-placed by the James Webb Space Telescope. The Tea Party HATES anything scientific, and they HATE NASA, so they cut the JWST funding out of the PROPOSED NASA 2012 budget, ALONG WITH ALL THE JOBS that would go with it. I haven't kept up to date what's happened since Congress went back into session, but you can probably find something here:

http://spacenews.com/

http://www.livescience.com/

Obama may have to make it an executive directive/order to get the JWST on the launch pad, ALONG with all the support jobs that go with it. PAY ATTENTION to who you vote into Congress next time, assuming you are old enough to vote and that you are United States citizen who is registered to vote. If you aren't registered to vote, go register.

Satellites that have enough fuel are either slowed down to burn up in the atmosphere or are parked high up out of the way. Recent satellites are designed with capacity to do this. Ones that fail control just get in the way and eventually (decades or years later) slow in the wisps of upper atmosphere and slow and burn up.
The Hubble will be slowed and burned up.

they will probably auction the items off for a high bit of money or donate or sell to a museum