I have a sprint spark lg4 just resently my screen go blank but when I tap it it won't light up sometime it do and some time it won't

you can use gmail account if you have one or if the tablet has a sim slot, Then do this:

1. From a Home screen of the phone, tap Apps > Contacts .
2. Tap Menu (located in the upper right).
3. Tap Manage contacts.
4. Tap Import.
5. From the "From" section, tap SIM.
6. From the "To" section, tap the desired location (e.g., Phone, Google account, Sim, etc.).
7. Tap OK.
8. Tap the desired contact(s) then tap IMPORT.

then once copied just enter email add or put sim in the tablet and it will sync all your contacts. If for some reason you still dont have the full list, on the tablet, go to contacts then menu (options), then contacts, contacts to display then select "All Contacts" to display everything.

1. Swipe down from the Home screen to pull now the Notifications shade.
2. Tap on the Settings icon in the top right.
3. Now find Tethering and Wi-Fi hotspot and tap on it to select it.
4. In the next menu, tap on Mobile Hotspot.
5. Turn it On at the top by tapping on the On/Off toggle.
6. Hit OK on the Attention screen advising you that WiFi will be turned off.
7. Follow the directions at the bottom of the screen to connect another device

overheating issues,

could be the motherboard or switch but the sewing machine
needs to be checked for sure

The DVD laser pickup is at the end of life, replacement of assembly the only option, cheaper to replace the combo unit.

First when tapping changes the picture you have somewhere a bad connection; in electrical board or wiring.
When the screen goes blank after a while means some capacitor is bad/old.

I think you must hard reset your device (set it to its factory defaults), in order to get rid of such a condition. There are some posts around handling this subject, like this one.
Hope you are able to sort your problems out. Carlos

1. Turn off HTC Home Sprint and Today Timeout. Settings -->Today --> Items --> Uncheck Today Timeout and HTC Home Sprint
2. Turn off Activesync. This can be done by closing activesync and going to Settings --> Phone --> Services --> Time synchronization and uncheck time sync. This will stop activesync from starting all the time

3. Turn Roaming to "SPRINT ONLY". Settings --> Phone --> Services --> Roaming --> SPRINT ONLY
Open the Task Manager (top right corner icon), clicked on the “tool” icon, then the “button” tab, and changed the “Enable the X button to end running programs,” selection form “End programs by tapping and holding X” to “End programs by tapping X.” Now, when you tap the “X” to close a program, it actually closes, and frees up more system memory. The same result can be achieved by tapping and holding the “X”, rather than changing the setting, if preferred. The objective is to CLOSE the programs and free up the memory.

if you tap the back of screen and it goes on and off chances are its loose ribbon cable ,
every time you open and close lid , it will tug on it a bit, if the light goes off then inverter problem

try using a new battery or tapping in...that happens to mine sometimes too