After installing ubuntu 9.10 I shut my computer down. When I restart I get nothing and am unable to reinstall. Why?
Ubuntu 9.10 reached end of life on April 30th 2011. It is now November 2012, 1 1/2 year later.
You most likely are affected by a bug in the 9.10 release or have a media that is somewhat damaged where either the install did not get finished correctly or some other issue prevents the system to boot.
You should download a newer version of Ubuntu. Bugs tend to get fixed with newer releases (well we sure hope a newer release never regresses ;) ).
The 2 options would be either Ubuntu 12.04 (LTS) or Ubuntu 12.10. If the install still have problemens please create a new question with as much detail as possible. If you do not like Unity 3D you could also try Ubuntu with Gnome 3 or any of the official alternatives, like Xubuntu or Lubuntu.