I believe my laptop is on sleep mode cos when i switch the power button the power indicator light came on but the screen was b

When a laptop is in sleep or standby mode, you should see the power light flashing slowly on/off.
If power light is not flashing slowly on/off, it's more likely to be a screen problem.

Look closely at the screen whilst shining a torch at it. if you can see a faint image of Windows on the screen then it needs a new backlight.