My macbook pro won't go past grey screen :(

I was on my mac I deleted a folder called usr and then it freezes. My battery was at 13% so i just let the battery die. When I connect my charger it goes to the grey screen a bunch of stuff pops up and it tells me to restart my computer. I hold down the power button and nothing happens I put the osx snow leopard disc in the drive to see if it would do anything but it didnt and the cd wont eject. Please help it is urgent

If you deleted your USR folder the machine will not start because that folder contains important system files. You will need to reinstall Snow Leopard in order to get your system back to normal.

If you can't restart it with the charger attached, try removing the battery from the machine, put the back on, and see if it will restart that way.

I deleted the use folder since I had never seen it before I thought it was a useless folder. I put the snow leopard cd in the disc drive it didn't do anything and the cd won't eject. I can't take out the battery since it is built-in.

Holding down the power button long enough should shut off the computer. If it doesn't you might have to wait until the computer dies. When you start the computer hold down C to boot from the CD.