I have ubuntu 11.10 installed on my netbook. When try to restart my computer the ubuntu logo opens and it attempts to restart. However after the ubuntu screen disappears it goes to a black screen and my computer just stays on. It won't reboot to grub allowing me to choose between windows or ubuntu
We need some more information to really help you.
What kind of netbook are you using?
Did you install from a Live CD or from Wubi (windows installer).
What graphics chip is your netbook using?
But for a start:
To bring up the Grub menu right after restart you have to press and hold the shift key after your Bios logo is shown (ca. 1-2 seconds after turning the power on).
Now please select the option 'Recovery Mode'. It should show you a purple screen with some options please select the option 'remount' and after that hit the 'netroot' option.
You should now be at a commandline looking something like this:
now please type
Ideally the ubuntu login screen is shown.
If not please post the output this command gives you.