How to Fix Your Digital Camera
While you can't open up a camera or camcorder and fix it quite as you can with a PC, you still have a number of ways to prevent camera or camcorder issues from ruining your perfect shot or cinematic masterpiece.
If your memory card isn't reading or writing properly: Some memory cards--usually SD cards--have a small notch that can lock the card in "write-protected mode."
If your card has that switch, try flipping it back and forth--it might be stuck. If the switch is broken, however, you can't do much besides buying a new card.
Sometimes cameras have problems using memory cards that have been formatted for use in other cameras. In that case, back up your data on the card and reformat it in the new camera; you should then be good to go.
If you're having image-quality problems: Repairing a point-and-shoot camera's lens or image sensor typically isn't worth the time, effort, or technical expertise needed, so if yours was damaged you're probably looking at getting a new camera. However, you can try a few other things before buying a new camera.
First off, wipe the lens with a soft dry rag (don't do that thing where you breathe on it first--the moisture can fog the lens over time) to clean it.
If you're seeing a lot of "noise" in your images, see how a few shots at a lower resolution come out; if your camera has a smaller lens and a high-megapixel image sensor, you might be better off shooting at a lower resolution unless you absolutely need high-res images for large prints. Also, check your ISO settings (if your camera lets you tweak them)--read "Eliminate Noise From Your Photos" for more tips.
If your audio feed is crackling: Your external mic connector might be loose. Secure the connection, and try again.
How To Fix Your Smartphone
If your phone won't turn on: Pop out the battery and try another one, if possible, or try connecting it to a power adapter or powered USB port. It's not always a power-related problem; if you unlocked your phone or flashed it with custom firmware, that can interfere with the normal boot process, but not with its "PC mode" functions, which might let you restore the original firmware.
If you can't connect to your service network: You might just be in a dead zone--and you can't do anything about that. However, if your voice service is working just fine but your data service won't connect, try switching your phone into Airplane Mode (for Android phones, you can usually just press the power button once to bring up a menu and select Airplane Mode), and then back into regular mode to reset your data connection.
If your phone is slow or crashing: More apps and more data on your phone mean more problems. Both BlackBerry and Android users will want to grab a process viewer/task manager app and a file manager app to help keep your phone as clear as possible.
If your battery is draining too quickly: Batteries don't live forever, and if you're using your smartphone to play music, keep up on Twitter, and give you driving directions while you're taking a call, it's not going to last long at all.
However, it might also be running down prematurely because you have unused apps and processes running in the background, so a task manager app will help you eke a little more juice out of your phone.
Also, turning off services like GPS and Wi-Fi when you're not using them will help, as will sticking to Wi-Fi for Web browsing when you have a usable network.