My laptop turns off without any reason

After I turn on my laptop it works fine for 25-30 minutes and after that just turns itself off without any warning. When I turn it on again, it works for some time and then shuts down again. What is going on? How can I fix it?

Most likely you experience a laptop overheating problem and it would be fixed by cleaning the cooling module – the heat sink and the fan. The notebook processor produces a lot of heat when the notebook is turned on. The cooling module helps to keep the CPU cool when the laptop is working. The cooling module includes two parts: the heat sink and the cooling fan. The heat sink is attached to the CPU and helps to conduct the heat from the processor to the radiator. The cooling fan blows on the radiator and helps to disperse the heat produced by the CPU. The laptop will overheat if the heat sink radiator is clogged with lint and dust or if the cooling fan stopped spinning.
If your laptop shuts down after some time without any reason and warning, check if the cooling fan spins. Usually it makes some noise and you can hear it. If the fan works fine, then check if the heatsink is clogged. In some cases you can clean the heat sink with compressed air, just blow inside the fan openings on the laptop bottom. If the heatsink is completely clogged, then it is necessary to remove the heatsink for cleaning.