Nokia Lumia 635 won't turn on
No matter what you do, you can't get your Nokia Lumia 635 to turn on.
If your Nokia Lumia 635 won't turn on, especially if it has not been used recently, you may simply have a drained battery. Plug your Nokia Lumia 635 into your computer or AC adapter and see if anything happens. Make sure to use only Microsoft Mobile approved chargers designated for the Nokia Lumia 635 or you can also use a compatible USB cable to charge your battery. Ideally your Nokia Lumia 635 will recognize it has been connected to a power source and charge its battery. You can double check your phone recognizes that the battery is being charged because seconds after you connect the device to the charger it gives a little vibration and the screen shows a "battery charging" symbol. If your Nokia Lumia 635 will no longer charge, the battery must be replaced following this guide Battery Replacement. You can purchase affordable batteries online.
It is possible that it appears nothing is happening because the display is bad. If you hold the Nokia Lumia 635 up to your ear you should be able to hear the hard drive spinning and feel it vibrate. If the Nokia Lumia 635 sounds like it is working properly but nothing is visible, it is possible the display is bad and must be replaced.
Bad Power button connection
If the Power button is not seated correctly, it is possible that the Nokia Lumia 635 will not turn on. Be sure that the bar on the Power button is completely flipped down to ensure a positive connection.
No audio or distorted audio
Your Nokia Lumia 635 turns on and appears to work, but when you plug in headphones or speakers, the audio doesn't play properly.
It's unlikely your headphones or speakers are bad, but it's worthwhile to eliminate these as the source of your problem at the beginning. Try your Nokia Lumia 635 with another set of headphones or speakers just to make sure that the problem is with the Nokia Lumia 635.
Bad audio jack
The most likely cause of audio output problems on Nokia Lumia 635 is a bad audio-out jack. You can purchase a new headphone jack and replace it by following this guide to Audio Jack Replacement.
Your Nokia Lumia 635's camera is not working
Your phone will not let you access the camera if it has a low battery. Sometimes the camera will open but the flash will not function. It is possible this is due to the fact that you have low battery. Make sure the phone is at least over 20% charged.
Missing Camera Icon
It is possible that the camera icon is unpinned from the task menu. You have to scroll to the bottom of the task menu and click on the right arrow. Then scroll down until you reach the camera icon, hold it, and then click on 'pin to start'. Your camera is now available on the task menu.
After discarding the previous problems, it is possible that the Nokia Lumia 635's camera could be broken. You would need to purchase a new camera, and if you want to replace it by yourself click on this guide for Camera Repacement.
Your phone's screen is scratched, cracked, or completely broken
Assure malfunctioning screen
Turn on your phone and make sure you can actually see something on the screen, even if it is not recognizable because of the broken screen you should be able to at least see the light coming off your screen. If you do not see anything, the most probable defect is that the motherboard of your Nokia Lumia 635 is burnt. Follow this guide to Motherboard Replacement.
You will need to purchase a new screen and replace it. If you want to replace it by yourself click here.
My phone case is broken or you want to change the case color
You have to purchase a new case. Make sure you have the appropriate tools so you do not damage the case when removing it. Once you are ready, take off the back case and replace it with the new one, follow this Case Replacement guide.