Hi and Welcome to TSG!
FIrst the basic suggestion. Press ctrl + alt and any of the arrow keys.
Now the advanced stuff if the above doesn't work, check your graphics card settings.
Do you happen to know what graphics card you have?
If not go to start > run > type dxdiag
When asked click yes
Wait for it to finish the scan, and then go to the display 1 tab, and tell me the manufacturer and name.