what do you mean by "re-input" everything?
Did you reinstall windows? if so did you install the correct graphics drivers for your computer after installing windows?
if you go to the support section of the manufactures website and search for the model number of your computer you should be able to find the correct drivers for your computer, at the very least it sounds like you need the graphics (video) driver, but it would be a good idea to get all the others and install them too while your there.
(or it might be as simple as right clicking on the desktop, select properties, then click on the settings tab and move the screen resolution slider up)