I downloaded the game but it won't go into full-screen mode for some reason when I press F4 it stretches a bit but everything (visuals and text) of the game are blurred and the quality is destroyed. Can somebody help me?
Well, yeah, it should look a bit blurred while in Fullscreen mode, that's how rpgmaker 2000 works, unfortunately.
Now, if it's really blurred, that's a problem. Can you make a screenshot of how it looks?
Also, you can try to play with the .exe properties, too (especially the ones below that are about scaling, resolution and stuff).