Screen resolution problem after game crash

Hi there,
I have a Dell Inspiron Desktop which is running on Windows 8.1, last night I was playing NFS most wanted and the game crashed severally, my screen resolution has changed dramatically and I have very large Icons which are not fitting the screen properly, I have tried to restart the computer to get the icons displaying properly, Display is stuck on 800 x 600, there are no other options available, how do I get display back to normal? What could be the problem and how do I solve it?
