Low screen resolution

Hello there, i got big problem with my screen resolution. I can't change it. My PC is Sony VAIO Intel pentium 4 inside. Few days ago i turned my pc on and i saw the message on black screen. The mesage was: 1: Analog input cannot display this video mode. I tryed to Shut it off and on again and it was no changes. Than i deside to use my reinstallation sc to repair defaults in my system. The reinstallation CD i have is not the original manufacturers CD that comes with computer but its Windows XP professional, the same thing i had in it earlyer.After the proces of repairing was done, the message was gone but the picture was bad quality. when i go to Display properties/settings, to screen resolution, isaw that the resolutionwas automaticly set on lowest level which ic 640 by 480 pixles and i cant drag the slide to specify the screen resolution and the color was also set on Lowest level on only 4 bit and i cant change it. I tried to go on ADVANCED/Monitor/Propertise and there is the properties buton but it won't open when i click on it. Please Help me A.S.A.P. because this computer is one of the MAIN computers in my music productions Studio. Thank you up front...