Graphics on my computer

I had promblems with my computer, so I did a system restore, everything is fine with the expection of the display on the monitor. Last January I had a promblem same promblem I have now with the display. The color was horrible the display was ridicoulsly huge, and in the display properties, 16 bit colors is the only option. Also the only option for pixels is 640 by 460. And I can barley read anything, just as it was last January. They installed a new graphics card NVIDIA, (in january) but we never recieved a disk. Of course we should of asked for one, or somehow did a backup. Now the color and display is just how it was at that time, horrible. with 16 bit color and 640 by 460 pixels. Ive tried many things and I can't find the solution.

And ideas on what I can do now to get the color and display back to how it was before the system resore, would be very appricated. Or how to somehow get a disk so the comp. can recongize the graphics card.