Sounds like you uninstalled your video drivers.
You'll need to figure out what brand video card/chipset you have, then download and install the latest drivers from the manufacturer.
If you post more details about your system, someone might be able to help narrow your search.
I was attempting to uninstall an unwanted program I had recently downloaded and a window message stating that to uninstall I had to change my monitor to vga so I clicked yes.Now my monitor has only one option in settings,16 colors.How can I change to list all the settings I had to start. I have computer built my a friend so it has no name but my monitor is a NEC Multisync FE700+. Would appreciate any help. Thanks.