Every laptop is different. We can't help you if we don't know what you have. We also can't tell you if you're files are safe until the machine is diagnosed. I recommend bringing it to a local shop. It is much easier to bring it somewhere than trying to figure it out yourself. we could spend hour walking you through steps that may not fix the issue. These types of issues are best dealt with hands on.
You could try:
1)holding the power button for 30 seconds, then trying to boot it.
2)remove the battery and the power cable. press the power button repeatedly for 30 sec. plug only the power cable back in and try to boot. then try with battery and cable.