Hello friend, how are you? Your problem occurs bcz you haven't install your VGA Drivers.
To install VGA Drievrs, first you must have CD that contains these drivers. Usually CD that come with your motherboard has all kind of drivers e-g VGA Drivers and Sound drivers etc...
To install VGA Drievrs, insert the driver CD into your CD Drive. Now right click on "My Computer" and select properties. You can see four tabs on the top of the dialog box just open. At first you will be in the "General tab". Next is the Device manager, so click on the "Device manager" tab and you will be in the device manager. Now you can see a category "Display adapters" in the list with plus sign before it. Click that plus sign. Now you can see the expanded entity. I think it will be "Standard Graphic Adapter" or something else but the first word is "Standard
". Double click on it and press the driver tab at top of the newly opened dialog box. Then press the "Update drivers" button which is on the left side. Now leave the first option as it is and click "next". In this dialog box "check the ckeck box labled as "specify the location" and click browse. In the browse dialog box, browse for your VGA drivers on the CD you have inserted. I think the path will be like this e.g Drivers>VGA>....>win98 or win9x.
Then press ok. Then press next. It will recognise the drivers and then again press "next". Now It will start installing your VGA Drivers. After successfull installation, restart your PC, it will automatically set the right resolution.
Take care of you and others and be happy.
Bye...
Dur-E-Wahab