Once you have double checked to be sure you know what you need...
driverguide.com might be a place to go, as I have found all drivers I have needed from that website.
You will need to register for free in order to have full access to that site. You can do scan from that driverguide.com. which will tell you what drivers you need, what drivers you need to update, and whether or not driverguide has it available.
If nothing works, try contacting dell technical support, with computer model, serial/product number, and maybe display driver device model info handy.
Good Luck.