2007 Macbook won't start. SMC reset useless.

My 2007 Macbook won't boot up. No grey screen, no white front light, no fan sounds, etc. Battery test button shows 4 green lights, and the charger plug shows a red light. Over time, the charger has increased battery charge. I followed suggestions to remove the battery and hold the power button for 5 seconds in order to reset the SMC, but that hasn't made any improvement. My computer was working perfectly fine some 12 hours ago, and I'm not sure what to do at this point, as my computer contains notes from college courses that I'm currently taking. Would LOVE to get my laptop usable again.