For some reason my computer has reverted to using on 16
colors and has the smallest resolution available. When I
attempt to change this, I restart the computer as
instructed and the computer restarts but without the
desired increase in color/resolution.

This happened to me a few months back and I went through
many suggested solutions (including re-installing the
video card) but it turned out that I had to re-install
the plug and play monitor as for some unknown reason the
monitor was installed twice. However this is not the
problem this time.

Any suggestions would be very welcome.